Cycle issues

Before getting pregnant my cycle was so regular and 30/31 days long and only bled for 3days. I got pregnant January this year but at 14 week I lost my baby due to Edwards Syndrome on 9th April, I bled for 4days. I had regular scan to check my womb etc and things seemed to be gettin bk to normal. I had a period in May on 13th, very heavy to start with them but only latest my usually 3days (meaning my cycle was 34/35 days) I was told it was ok to try again so been BD a lot. I'm now on day 37 of my cycle AF not shown up yet. I took a test two days ago, BFN. When should I test again? If AF doesn't show when should I go doctors?