My husband and I have been trying for months to get pregnant. I started taking prenatal pills a couple months ago. This month, my period came 4 days early, and only lasted 2 days.. Nothing like that has ever happened to me before. Also, my breasts are usually only sore for a few days during my period, but this month, they have been sore for the past 3 weeks ! My 2 day period was about 2 weeks ago. I took yet another Home PT today- still negative. That makes 3 negative tests :( Any ideas.. Could it be the prenatal pills throwing things off ?

It could.
But also light bleeding is comon. It could have been the placenta ataching. Watch and see if you come up with more symptoms. Nausia, back ache etc. (I didn't have many symptoms when I first became pregnant so not always clear give aways) also most hpt depends on the amoun. Of hormones you are giving off. I had troubles with them when I first became pregnant also.
Best bet? Go see a doctor, they can give you more clear info and tell you if tour are pregnant or not, or if it's just the pills throwing you off.
Good luck!
~Erica