late period, negative hpt.

In January I had a miscarriage between 6-9 weeks, the baby was growing very very slow so I was 9 weeks by LMP but the baby measured 6 weeks. I got a period in February and in march, and now I'm currently 2 days late for my period this month. I've taken 2 pregnancy tests and they've both been negative. With the last pregnancy I didn't get a positive until I was 8-9 days late, but I figured that was just because of what happened the last time. I know stress can cause a late period but I don't think I'm stressed, I feel fine. But I've not had any of the usual symptoms for pregnancy or af. I guess I'm just wanting to see what anyone else thinks. Thanks in advance!