Your mother only knows how to fulfill one persons needs - her own. Accepting that she is incapable of considering you or anyone else, is the beginning of finding your way out of this IMHO. As long as you want her to do better as a mother (or be a better person), she will frustrate you like this. For me, when I radically accepted that my mom wasn't capable of the things I wanted from her (as my mother), I was able to better accept that she "is who she is", and it became easier to set boundaries (for myself).
I would not be surprised if your mother picked that time to tell you she needed a doctor because you had just been at the in-laws, and she was needing
attention. If this is the case, you obliged her this need in a few ways:

As soon as mom mother became aware that I got home, she calls and says that she has to go to Urgent Care because she believes she has a UTI. She tells me how she will take a cab and I can get her after.
So when something like this happens, "check in with yourself #1". How you you feeling about this demand? Are you triggered? Are you feeling strong enough to manage your emotions around her? Is this a real emergency? Assess the situation in these ways first. Don't just "react". If the answer is yes and you are feeling ok, you can humour her and go help. If the answer is no, "Mom, I'm not feeling well either, so I can't come right now. If you need to go to urgent care now, try calling a friend to drive you, or else call for a taxi. I hope you feel better soon. I have to go now. Bye." This is a boundary. Do you see how this boundary is for yourself...and not your mom?
I will get her to not feel like a terrible daughter or look that way to the outside world. I pick her up and yell at her.
So she has trained you to have these guilty feelings and obligations, to have her own needs met. Going to get her, to not feel like a terrible daughter is the wrong reason to go get her. This is why it's important to check in with how you are feeling, before you even respond to her demand. Metaphorically, when she says "jump", you say "how high mom"? Why will she ever stop demanding things of you, when you keep doing what she wants? Since you always give her what she wants (even if you are angry), her demands are working for her. This is called positive reinforcement. If you yell at her, it doesn't matter, because I'm guessing she was raised being yelled at, so that is normal for her. Nothing in her behavior will change, until you change how you respond to her demands. It sounds like she is controlling you, and you are letting her, probably because you love her, and genuinely want to help her. But with BPD, we need to learn the skills to manage these behaviors. Yelling at her when you picked her up is a big clue (after the fact), that you weren't feeling well enough to perform this demand at that moment.
"What are your symptoms mom?" If she stutters, suggest she wait 24 hours to see if it clears up on it's own. If she responds with all the right symptoms for a UTI, then with gentle caring, suggest she call a taxi.
Or, if you have call display, and don't feel up to her charades, don't answer your phone or texts. If it's an emergency, she can call an ambulance right?
As I get home, she is already calling saying that it is a two hour wait and can I take her elsewhere. I say, "No, you have to wait." Two minutes later, she texts me to say they said now they are booked and can't take her. I start to drive to her and thought, "let me call to see if I'm right and she is lying as usual." I explain to the girl and she says, "yes, we are taking people, as long as they are willing to wait." I call my mother back and, like I would a child, demand her walk back in and wait.
So you handled most of this really well, especially where you "drew a boundary" and told her she could manage the 2 hour wait (after her first call). Maybe remind her gently that everybody has to wait, and you have the confidence she can wait her turn like everybody else. She won't have thought of that. Checking the facts with the urgent care center was a good idea. But understand that BPD's who are escalating, are wanting a reaction. It feeds their emotional needs. Again, this is why it is so important to "check in with how you are feeling" to assess whether or not you are in a healthy enough state of mind to deal with her drama. Instead of treating her like a child when you called her back and "demand that she walk back in and wait", it is
critical to keep a calm voice, and gently tell her that you have called and checked with the clinic, and they said that they are seeing people, but she just has to wait her turn. You are not available at the moment, but she is in good hands, and can call you after she has seen the doctor." See what is happening here. You are better managing her behaviors. She gets to learn from her consequences. Next time, she can call ahead to the clinic first to see what the wait time is. That is not your job.
I am here writing as I wait to get her. This is my life. I think I will have a relaxing day and she ( or some other family member) just always uproots it. I don't know if I've ever mentioned this but her sister and niece (my aunt & 1st cousin) also have this illness and constantly lean on me for everything too.
They do this because you keep jumping every time they have a demand. What will you do to change this pattern?
I am proud of myself but I still can't fix the angry feeling inside me.
Work on learning the "tools" this website offers, instead of reacting to her demands. When you have more tools to navigate her behaviors, you will get your life back, and slowly, the anger will be less. It takes work and effort to learn these tools, but it is really worth it to get our lives back.
Tools: radical acceptance, SET, boundaries, asking validating questions, don't JADE, mindfulness and distress tolerance (check out "how to get the most out of this site). These things really do work. I can vouch for them. I used to be one of those people that said "how high" when my mom said "jump". I don't do that anymore. Surprisingly, she has found many other people to do the things for her that I don't do (H and I still do PLENTY). But the more you do, the more she will demand. The more she demands, the more frustrated and hopeless you will feel. She will pick up on this and eventually all her bad feelings will be your fault and she will rage at you. The only healthy answer to all this chaos and distress, is to learn the relationship tools on this board, because they really do work, when they are used as they are meant to be used.

It can get better.
