switch my bcp because my brand was on back order

I went to my Dr to switch my bcp because my brand was on back order. He change my pill. How ever I did not take the last week because a guy I was talking was coming in town at the end of Aug and did not want my period on so I jusy start the new brand. We had sex 4 days into the new pack. I start spotting the next day for two weeks. And at the end of Sept my period did not come on. so I stop taking the thinking its the problem and my period came but was really really lite and went off not even 2 days later. My breast is sore by that all. And 4 all tests said Neg. So whats going on with my body help plz