Help! Is this normal?

Hey ladies so I have some questions about my period. I am 23 years old, I first got my period when I turned 12. I had it maybe three times, then I didn’t get it again till I was 18. Since then it’s been very inconsistent. I’ll have it for like two days and then not have it for 4 months. However whenever I do have it, it is always very heavy. Like blood clots the size of golf balls. Masturbating will sometimes cause them to happen as well. Also I’m a virgin so no chance of STIs. I don’t really ever get cramps when I am having my period. I’ll occasionally have a sharp shooting pain but it will go away quickly. Let me know if you have any advice or similar experiences. I’m probably going to schedule a appointment with a doctor, but I wanted to see what the community had to say. Thanks!