Need advice please.

Lesley
Hello. My husband and I have been TTC since October. We had a miscarriage in March and ever since my cycles have been a little strange (coming around CD 25 instead of 28 and only lasting 2-3 days instead of 5-6). I was supposed to get AF  on the 19th and she hasn't come yet. The past 2 days I have had cramping and lower back pain, so I just knew I was out this month. Well... For some strange reason I took a test this morning and it came back positive!!!! I'm in shock and beyond happy about it, but very scared because of my previous MC. Has anyone had cramping( that feels like AF cramping) and had a BFP???  I've tried to google, but it's no where as helpful as all of you. Thank you