Hi Smile41869!
You sound as if you are dealing with a ton of stress right now! Kudos to you though for sticking with your Phd nearing the final completion.

Lots of work would be the understatement! Congrats!
Next let's think about your options here. I am really sorry that your uBPDm is going into a rage over the lack of communication. It's not what you need right now. You need care, concern, and a cheerleader to encourage you to keep going, that you are almost there, and you can do it. She is failing you in this, isn't she?
Sadly when major things take place in our lives, for those of us who are the children of a BPD parent, we threaten to take away the attention from them and focus the limelight upon us for a brief moment in time. They cannot handle it. It seems so unfair, and for myself, I would've liked to have the attention on me for having achieved something, as I'm sure you would too, instead of that of our uBPDm.
One of my initial thoughts was this:
1. If you contact her now, will it help her to be any less angry?
2. If you wait and contact her after your 3 weeks are past and your phd is done, will that cause her to feel any less angry?
In other words, do you think she'll be angry no matter when you contact her? If so, then I wonder if you have nothing to lose. It could buy you some time to care for yourself and finish up your important things first. Perhaps you could send a short text that you'll check with her soon about the tests, but for now you have to concentrate on you for the next few weeks. Have someone else read her texts and filter them for you for the next few weeks. You can chose to not answer them for this span of time, then re-look at it after the major stress is off of you. It is a boundary setting, and is for you, not for her as the BPD will not respect our boundaries.
What do you think of these ideas?
Wools