Pregnant?

Ok ladies. I started taking birth control in July of 2014. In March of 2015, I stopped having periods. I discussed this with my doctor, and she said it was totally normal. I got married in May, and my husband and I decided to prevent pregnancy using NFP. I got off of the pill in early September. I had a very light, 3 day period about 3 days after getting off of the pill. Since then, I have not had one. Before BC, I always had really normal, regular periods. For the past week, I've been really bloated and irritable, fatigued, and occasionally nauseous. I've taken two pregnancy tests, both negative. I guess my question is, could my period just be off after getting off of the pill? I recently started charting my BBT and all of that stuff for NFP, and I'm thinking I may not have ovulated when glow said I did. I'm very confused!