Last 3 mos unable to conceive. took bbt this month and had no temp rise 4 dpo. confirmed with opk. when should i see doctor- start of next cycle?

Around Cycle day 21: If you want to become pregnant but are not ovulating, its a good idea to see your doctor. Every doctor has their own preferences. Personally, I like to see patients who may not be ovulating around cycle day 21 because I can do a blood test that will tell me if they are ovulating or not. Call your doctor and find out what his/her preferences are. Best wishes!