How long do I let my period go on before I should see a doctor

I recently got my first Depo-provera shot and I was told by my doctor that my periods would be irregular and eventually go away completely. I have been on my period now for over two weeks and it's extremely heavy with pretty sever cramps. I don't want to see a doctor unless it's really necessary because I don't have health insureance. Any one else here on Depo-provera aware of these side effects?