Hypothyroidism :(

Anybody my age (25) TTC their 2nd child? Ive had thyroid disease since I was 12. Didn't think it would be a problem to get pregnant until now. I was pregnant at 18 with my first child. (Not planned of course) my son will 7 yrs old this year and he wants a sibling. I've been trying for 6 months so far. But I'm really starting to think my thyroid condition is the problem. AF was due on Jan 25th. I'm two weeks late today. I was spotting for like 3 weeks. The spotting stopped. I keep getting BFN. I seriously don't know what's wrong with me. Anybody can relate somehow?