Irritated.

Maybe it's the pregnancy hormones but I'm extremely irritated.. So basically my fiancé and are I living at his parents house and I'm 20 weeks pregnant. My fiance's sister has a 7 week old and I just feel his sister ang her family takes presidence over the rest of the family. Like literally she says jump and everyone jumps. Well my fiance's mom recently bought us a really nice co sleeper crib and my fiance's sister was over and said she wanted to try it with her baby and without question his mom just gave it over to her. I was upset about it because that was bought brand new for us and now it's going to be used and it wasn't even meant for her!!! I don't want to say anything and be rude because his mom bought it but seriously? I'm just tired of everything being all about her. Like I'm pregnant too and I matter too. Like sheesh, what else is going to be bought for us that she will take!? Don't get me wrong, I am grateful but not when things are taken from me. Ugh. Advice please!