Baby fever! I have 2 already

Hello, I am a mom of two. My son just turned 2 April 14th! My daughter is 5 months. She was born November 19th. I am having baby fever! My daughter is still a baby, but I find my self saving all her clothes, because I think me and my husband will have another one day. My sister in law has a 4 year old boy, and she is almost 3 months pregnant. She wants my baby girl or baby boy stuff. She said once she finds out, then she will come over to go through all my baby stuff. I do not want to be rude and say I am keeping it just in case we have another one day. My mom in law was trying to tell me to get my tubes tide after my daughter. She was in the room with my husband when I gave birth. I will add, me and my husband have been with each other since middle school. I am 22. He is 23 years old. We have our own place and land, We have a car, he has a good job, and he works 50 hours a week. We love being parents. My question is, Do I seem selfish to want to keep my baby stuff? (Just in case we have another). I have always pictured having 3 kids. I do not understand how many kids I have should have anything to do with my mom in law or sister in law. I have my babies 24-7. No one else takes care of them but me and my husband. Sorry for the rant. I am a stay at home mom, and do not have any friends. Lol