AITA for expecting a birthday party ?

A couple of months ago I went out with my now ex friend group before our final exams. Our first exam was on the Monday and my birthday was on the following Wednesday. I have been in this friend group for two years and Everytime we go out for one of our birthdays I make sure to buy a cake for the birthday girl with my own money as I live the closest to where we would usually go out to eat and would go out of my way to hide it right till the perfect moment. On this particular day we were having a picnic in the area we would usually hang out as a pre exam treat and although I was reluctant because of exam stressed they convinced me to go staying that I study enough already and that I’m doing too much work so I should stop taking it so seriously. I had to go home for a good 15 min whilst they were at the store to get snacks. On my way back to them it occurred to me that they may have planned something as they had the perfect chance to buy a little cake and candles whilst I was gone. Turns out it was my wishful thinking. There was no cake and not even a mention of my upcoming birthday.

I know I shouldn’t have expected something but the least they could’ve done is brand the outing in my name. No one even got me anything when the day actually rolled around but I excused it for exam stress and hassle and was grateful they didn’t forget it till the day like last year.

I don’t know if overthinking it or if it was just all the negative things this group had made me feel over the two years but this just hinted at me that they didn’t value me how I valued them , and I’m not saying this as a one of but this would happen one other occasions too.

did I deserve something ? Or am I the asshole for wanting to make a pre exam outing about me.