Moms and periods don’t mix well?

So here’s my story: I’m currently 15 and got my period 4 years ago. My mom and I have never been close. I had recently switched medications and had to go to my normal checkup doctor to discuss what I was feeling. It was unrelated to my period, but it did make my flow change a lot. I started to be super irregular and bleed so much more than I ever have. I go through a super plus tampon in just short of two hours on my first three days. So I asked my mom to talk to the doctor about it, and my mom said I can’t. She says it’s normal and that girls will just go through those period changes in their lives. Which sounds believable but I’m in so much pain and it’s so uncomfortable and wet down there constantly. I just today looked at menstrual cups when we stopped at the store and asked to get one (in hopes to contain my heavy flow) but she said no. In the car she asked why I wanted it but all I said was because it can hold more and costs less. She says the last thing I need is to trap moisture in a dark area and that I will get an infection. My question is, has anyone else experienced these issues with their moms? Can they please help me get through this? What’s your mensural cup experience? And any other advice!!! I really need it because I have no other options and am frequently active and unable to go to the bathroom.