I don't know if I'm being dumb

Andrea • 24 & married to the love of my life. My son is my world. Baby girl Feb. 2022 Self love & positive vibes. IG:_reinalv_
So my fiance and his mom have a rough relationship, it's a really long story and they're always on and off. Well when me and my fiance started dating they were good and they loved me and everything they've just always hated that I was quiet because they thought I didn't like them (That's just how I am as a person). So I started being more vocal and everything was great. Then my fiance got his older brother to start talking to his mom again (they also had bad problems also a long story). Well his brother had a girlfriend and they honestly started treating me and my fiance like crap. They have always babied his older brother since they were little. We would go over to parties and stuff and shed ask everyone if they wanted food and served them but told us we could get food from the kitchen and little stuff like that. Well his brothers girlfriend just had a birthday and she posted a pic of a Michael khors bag and said it was a late bday present from my MIL. She always gets her stuff even when theres no speciak occasion. I'm not jealous or anything just kind of hurt because in all the almost 4 years of us being together his mom or stepdad haven't even wished me a happy birthday once. I dont care about the material things or anything but dang not even a happy birthday. Do I have a right to be kinda of sad about this? I'm not pissed, jealous or anything like that just slightly hurt. I haven't told my fiance because I feel like there is no point.