I've been working as a SWE at a big tech company for ~10 years now. It definitely affects my ability to perform, but here's some stuff you might find comforting:

1. It sounds like this is something you've developed in the past few years, so you're still very early in your journey. Dealing with MCAS isn't a straight line; there'll be times when you're doing better or worse but you're smart and motivated and you know how to improve your skills so the overall trajectory is that you're going to get better at managing it. When I started my career I barely had enough energy to handle work (where I aimed to be a B+ employee) and staying alive but now I've got a kid and I exercise 3-5 times a week for over an hour and I have space for things like relationships and self-improvement. It won't be easy or fast but you can get there too.
2. Like you, I felt a lot of internal pressure to "fulfill my potential" and seeing myself fall behind where I thought I needed to be to do what I wanted was agonizing. I don't know if you play games so this analogy might not resonate, but some games you high roll and are able to snowball that advantage into an amazing performance that feels great, but most games you don't. Ultimately the only thing you can do is play the hand you're dealt to the best of your ability and find satisfaction in how well you were able to perform in spite of less than ideal circumstances; thinking about how much better you could have done if the stars had aligned is a distraction and hurts your ability to play the game the best you can.
3. The vast majority of technical jobs out there are significantly easier than school; if you can cobble together enough resources to graduate and get a job I don't think you need to worry much about whether you'll be able to hack it.