I have these kinds of thoughts often. but it's not a good way to think about things, as in, at least it's always been damaging to me. you shouldn't invalidate your own feelings. if you're not doing "better," that's okay. you don't have to be perfect just because nothing catastrophic happened. or because you feel like if you pushed yourself harder things would be significantly better.
procrastination is never for no reason, and as you said, you feel like a lot is at stake. you have a lot going on! and unfortunately, no one has instructions that will make the nebulous "don't get it wrong" voice go away. it sucks. I know that feeling, and I empathize.
what's helped me is to sit down, preferably with someone I trust and who respects my emotions, and make a little "plan." not a full one where I have x, y, and z plus an emergency one, but just something that will make me feel like the world isn't going to crash down around me at any moment. for example, I had to sort out with my partner what we would do if amazon rejected a return I made because money is tight. even just knowing the future isn't a mysterious void had helped me.
additionally, my only safe space is also my room where I live. I don't know what your living space looks like, but things that have helped me is buying something small to decorate it and make it feel more like my own, possibly getting a small living plant (I have aloe and haworthia, they're very easy to take care of and it sparks a little joy when I see them growing), or even just tidying up a bit, or moving things around so that they're not in the exact same place. when I feel claustrophobic and confined to my room, I try to go on walks (weather permitting!) to remind myself there is space that is safe outside of the house. listening to music or podcasts helps me too, if that's something you also like. I try for at least twice a week and find myself walking more than expected because it's nice to have that break.
I wish you good luck on the cake! and apologies if none of this helps. I just feel like our situations have some things in common and wanted to reach out with what solutions I have for myself.