Ughhh!!!

So to begin with I just wanna say that I have no problem with my mother in law or anything like that but ugh I’m a little annoyed!!! So I had my baby 4 months ago ever since the beginning my mother in law has taken over everything. I understand it’s her first grandchild but she could have asked me as the mother before doing the stuff she did....but anyways fast forward to now. My sister in law is 3 months pregnant at her last doctors appointment she found out the gender of her baby which I thought was too soon to find out but I guess not 🤷🏼‍♀️ so her baby is a boy sooo my mother in law decides to offer her my sons things. Stuff that I had to pay for example my breast pump and all of my baby’s clothes... now i don’t have a problem with passing along his old things but she’s not even asking me she’s just offering them to her daughter like they’re hers it’s so upsetting because I had already promised some things to other people and I just feel like ughhh!! Am I wrong for being a little upset that she’s just offering my stuff or do I have a right to feel upset?