missed period but negative test.

Lilly

so I have missed my period.

my boobs are sore, I have heartburn, I'm nauseated and tired all the time. but the test says negative. I took several test and they showed negative at forst but then after a couple hours or the next day they turned positive. its not evap bc its not grey. the positive line is actually pink! I already have a baby that was born 10 weels early due to PRE E. PLEASE HELP. weve been trying to conceive again.