Office hysteroscopy 10 months ago biopsy normal put on prometrium (micronized progesterone) took for 3 months stopped it 4 months now taking it again would cancer develop short time?

No, not that: Type. Endometrial cancer generally evolves over years of unopposed estrogen. I'm not sure of an exact time line but usually there is hyperplasia with atypical on bx first. In your situation, 4 months should not be sufficient but u need to know the pathology of the original biopsy. You may not have a high cancer risk. You could also use it 10 days every 2 months and have period, talk 2 ur doc.