Honestly, you have no way of knowing what it was, and it's not that importtant in assessing your risk.
You do have a pregnancy risk regardless. It is a very small one. What you've described poses a greatesr tisk of transmission of bacteria, and thus, STDs or STIs. Please don't get the idea pregnancy is a bigger deal. More young people transmit and contract disease than become pregnant.
So. Obviously if your period is late next time, take a test. Likely, it won't be.
But it's time for you and yours to start regular STD and STI testing, as you already should be doing, and to take the time to learn about how to practice safer sex. For what you've described, at a minimum, you really need to WASH your hands in between, and ideally, you should both be using latex gloves.
The bonus there too is that then you also needn't even worry about that miniscule pregnancy risk, either.
(For the record, we're never out to scare anyone -- that's not our intent. What we're out to do is simply be as truthful as we can about the reality of these things.)
Editor and Founder, Scarleteen
My epitaph should read: "She worked herself into this ground."
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