Wow....your discription is kinda all over the place there...but I can understand your anxiety...
Well...I'm no doctor, but taking into consideration all the details you've provided, your chances are kinda slim to nill of her being pregnant. Keep in mind though, that ANY vaginal contact with semen still has a chance of resulting in pregnancy... so if you feel your concerns are serious enough, you should probably run a pregnancy test in order to ease your mind. There are plenty of tests on the market now that can give you a pretty accurate response several days in advance of when your girlfriend should be expecting her period.
Like I stated earlier, however, her chances seem pretty low for the most part. As for pregnancy symptoms and how long it will take to find out...well that's almost impossible to detemine. Pregnancy symptoms vary from woman to woman, some don't even show symptoms at all...and how long it will take to know for sure depends on her cycle and ovulation patterns.....there are many things that factor in that you need to consider.
For now...all I can really tell you is to try and relax....you're probably worrying about nothing...remember that the only way to REALLY prevent this type of thing at a 100% level is through abstinence....but if you really feel the need (And who am I to judge? We're all human afterall!) then condoms should always be at the ready...remember that a five dollar investment now can prevent 18 years of hard work raising a child later!
All the best to you!