Hello, for the last about 4 to 5 months I have been having severe periods that are lasting up to 3 weeks at a time with heavy flooding and big blood clots. I know this should not be normal, and I have no medical insurance. What should I do?

Have you looked into any free or reduced clinics in your area? Someplace like planned parenthood? Planned parenthood is often able to help with costs if you have no insurance. And if there's not a planned parenthood in your area, there may be some other sort of similar clinic able to help. I would look into finding someplace affordable even without insurance. This is definitely something you should get checked out as soon as possible.