Birth control

I’m going to get an IUD put in sometime next week. I’m super scared honestly, I’ve been reading some people experiences and some say it’s super painful and stays painful for months after. That sex because painful for awhile after. I also heard that you gain weight, which I really don’t want because I just lost a lot of weight. My mom had it and she said it was great for her. Does anyone have any experience or stories they wanna share?