Forgot My Own Birthdate

So today I kind of forgot it was my birthday. Not like I was expecting anything huge or even to remember at all, but I did forget entirely for the day and someone had to point out the date on their calendar. Then everyone started reminding me about how old I am now because apparently they noticed the day before and planned something for today. I feel a bit silly and guilty because my sister actually went out of her way to buy me cake at the bakery this morning since I wasn't even aware it was my birthday until she told me. It's like every time we have family gatherings, I act as if I don't care about anything, but then people do stuff for me anyway. Maybe I need to start pretending more that birthdays are a big deal just so they feel their efforts aren't wasted... or is it just better to be honest and say I'm not really into all the fuss? Also, my mom keeps asking why I didn’t tell her about how hard school has been lately, which reminds me of this time last year when she bought me an entire new wardrobe but I barely wore half of it because everything was too fancy for my style. Now I wonder if I should just be more open with them so they don't feel bad buying things that end up unused...