I guess it takes 2 to ...tango.
Chances are you won't get pregnant, since the ejaculate went into the condom after he flipped it (if I understand correctly).
Pre-ejaculate though, may contain some sperm-albeit substantially lower numbers than semen- specially if he had masturbated earlier and had not urinated any time after that. Urinating normally clears up any remaining sperm from previous ejaculation.
You should also post at the Teen Pregnancy Concerns
here at MedHelp for additional views, but my advice to you is , if you are sexually active and enjoy having sex, do it safely and explore your contraceptive options well.
I'm sorry to just be getting to your message.
You should never rub up against each other unless he already has a condom on or you'e on birth control because there is a chance you can get pregnant by doing this.
The chances are much smaller because it was pre semen which contains a lot less sperm.
At least he did ejaculate in to the condom and not in you.
All you can do right now is wait to see if you get your period. If by chance, you don't, then take a pregnancy test. I know it won't be easy but try not to stress because that could make your period late.
I highly recommend you get to a women's clinic. They will give you free condoms, as many as you want, and free birth control depending on your income. You're still in school so you should be able to get birth control for free.