Tired of hearing "you'll grow out of it"

It seems like I am constantly being told that I will grow out of how I feel. Even when someone doesn't know that I am trans I still find it rude to tell someone you'll grow out of something. My stepmom asked me the other day that if I marry a women if I would want to carry the baby since I want to have kids and when I told her I don't want carry a baby she said I will probably change my mind as I get older and it made me so mad because if though she doesn't know I am trans she shouldn't ask me a question then tell me I am going to change my mind because that's basically like telling me I am wrong. I am ranting today because my mom just did almost the same thing. We were talking about our chests because my mom is a size I and said she doesn't like it but wouldn't get reduction and I said when I am older I am definitely getting my chest cut off and she told me that I will change my mind when I am older. I couldn't say anything at the moment because my brother was there but she knows I am trans and has never said anything in the past when I mentioned how much I wanted my chest off. I am just so tired of people telling me that I am going to change my mind about all of this just because I am young.