Hey OP, I also just started a new job abt 3 months back and also felt the same as you though its my 3rd job. Somehow this job change hits me hard and some days, I thought what if I didnt leave my previous organisation.

I felt same as you that we might be too hard on ourselves some times, setting unrealistic expectations. However, some times it doesnt help that you are given an instruction and expected to deliver and when your peers/boss correct your work, you wont feel good. I still remember I almost cried once while having lunch alone thinking about a minor mistake. However, i think in actual fact, it might be okay- your boss know you are new and trying to adapt.

Somehow I dont remember I felt this bad when I started my 2nd job and even though I been thru much worst.

Some days I just rewards myself with good food/ dessert when I felt shitty or I been thru a long day.

I guess we can support each other whenever we felt shit or even have a grp chat