With this many polyps, it is highly likely that you have a genetic polyposis. In my case, I have MAP (Mutyh-associated polyposis). It's recessive and MAP is very rare. There is no one else in my family history that has it. Please ask your doc to to order genetic testing. (I had mine thru Quest 66 gene cancer panel). Having annual colonoscopies (since my 30s); I'm now in my late 60s) saved my life and my doc knows to monitor other areas as it can cause a higher risk of other cancers. Two years ago, I had a total colectomy with ileo-rectal anastomosis (TC-IRA) All told, I had over 150 polyps removed.
3 years is too long to wait for another scope, in my opinion... I'd be happy to answer questions if you message me.