I think im crazy! Lol

OK... So I had AF last month...I was due for AF on 1/26 and she didn't show until 1/29. It lasted for maybe a day, was somewhat heavy at the start ( I've had worse) and went really like quickly. I had taken a test on 1/29 and got BFN and have taken another on 2/2 and once again BFN... I am have horrible heart burn, odd crampy feeling, very vivid dreams, and omg sore boobs! We have been TTC for 4 months now. We Already have 2 girls, 4&7... But we were not trying then, they were "oh hey were prego" babies... My friend tells me I could be prego..... Thoughts?