Hi akeinator and Welcome!
I'm sorry you had the need to find us, yet glad that you did. You've come to the right place that's for sure. By the sounds of it you've read some other posts and already can (hopefully) see that you are far from alone. We will be here to support you as much as you need us to.  :)o let us know how best we can do that. The information here by way of articles and lessons is fantastic and I'd strongly suggest that you begin with the lessons to the right of this board as a starting point. They are here to help you to tackle some of the most common stumbling blocks in a BPD r/s and I'm sure that with practise you will find them really helpful.
I've also come to accept that I also have problems of my own and that these greatly exacerbate the issue, and I am going to try and focus on my own issues and not just talk badly about my partner, because I want to make this productive.
I must say that I find your above statement extremely admirable, along with your clear self awareness regards your own specific challenges in a r/s. Not many people would be so able to identify and own these things. Your therapist is going to have light work!
I'm sorry to hear about how you have been feeling lately, and it is understandable given the strain that can arise in a r/s of this type. It is important that you consider your own needs such as rest, as lack of these things can catch up on us.
Noticing that things are difficult right now is the starting point and the next step is to find ways to make things better. I'm confident that with the support of the wonderful membership here, with their own experiences and findings, along with the excellent lessons you can begin to see that you can affect the interactions you are having with your partner.
She never actually comes out and says something like that, but it can't all be me and my defensiveness and reluctance to ask for help, which is what the majority of our arguments focus on these days.
You're right, it isn't all you. It takes two people to form a r/s and both parties play a role in how things work. You can't change the behaviours your partner demonstrates, however your own responses to these can make a big difference in the dynamic, as I've said above. Hang in there. It also seems you are seeking help, by coming here and starting your therapy. Well done for both. Is your partner having any therapy or treatment at all? Where did her awareness arise from around the BPD? I notice she is undiagnosed.
Keep reading and posting. You can find your way through this.
Love and light x