that does sound normal there is always a chance of getting pregnant even if you take plan b or even the morning after pills and even with protection
I don't know about bleeding two days after. I guess it could be a period, if your period is still a bit sporadic. Mine took a couple of years to start coming regularly, so I would get surprise periods. If you don't think it's a period or it continues a long time, or you start feeling dizzy/faint, you should get to a doctor ASAP. You should go to a doctor anyway, just to be safe, because I cannot tell you for sure nothing is wrong over the internet (I'm not a doctor and I can't examine you).
And YES, is is possible to get pregnant the first time. If you have sex without protection, you can get pregnant. Period. Since it's only been two days, you can still take the morning after pill. Since you're under 17, you need a prescription, but you can get that without your parents knowing if that's an issue.
See this page http://eclocator.not-2-late.com/ec_teen/index.html for info on the morning after pill and how to find it. Note that it's most effective within 3 days, but still somewhat effective up to 5 days after you had sex.