Pregnant even if the typical signs aren't there?

I had sex exactly once any time in the past year, and it was 6 weeks and 1 day ago. I have been on the pill and we used a condom. I continued to take the pill and get my period on schedule - everything was completely normal. Being a college student, I am always a little fatigued, and I don't feel like it's really that much more than it should be - this is my hardest semester yet and I haven't been great with time management so I don't get a lot of sleep, and it feels a little bit worse than most semesters. But if it was 6 weeks ago and my semester started 10 weeks ago, I'm not sure if it could be from being pregnant. My diet isn't great and sometimes I get gassy when I drink soda or eat really unhealthy for a few meals/days, and that's happening so I don't know if it's from my diet or if I should count it as a symptom. Finally, I threw up 2 Sundays ago twice, and usually I don't get sick unless I took a multivitamin on an empty stomach, and my stomach has not felt great 2-3 times since then. Also this is into week 3 of a new type of birth control right now, so I don't know if it could be that. It seems like everything has other explanations, and combined with the fact that I had a normal period, I feel like I am not pregnant, I just want to know if anyone else has experienced a similar situation and ended up being pregnant...