Birth control: Is it possible to be pregnant and not know?

I started having a couple pregnancy symptoms about a month ago. I took a pt that was negative and the doctors was negative so we decided I start Ortho Evra (the patch) which I started the day I got my period June 6. I had some small clotting but not a lot of pain and it went away. I have bled lightly since I started the patch but the doctor said that could last up to 3 months. The part that I find so odd is that I have gained 6lbs and the last week or so I have had a huge increase in appetite, fatigue, moodiness, etc. I have spoken to several women who used the patch and they decided to switch because they had bad nausea. But NONE of them had those symptoms. Some suggested maybe I wasn't far enough along when I had the pt done. Has anyone ever experienced this? I don't want to seem foolish to go to my doctor with this but also don't want to feel foolish not to go to the doctor. Advice plz. Can you be pregnant then start birth control and not know you're pregnant?