Too good to be true?

After 8 months of trying I got this shock BFP this morning, AF was due yesterday. I got BFN 2 days previous and have had brown CM and cramps for the last couple of days so assumed AF was on her way. Only tested this morning as my partner was going to book in for sperm testing today. Afraid it's a false positive as was resigned to the fact it wasn't going to happen! I still have mild cramps and brown CM when I wipe. Is this normal?