Lots of watery discharge but no odour?

I have had sex twice unprotected with the same guy. After the first time, i got a burning sensation down below and it was itchy. I had lots of watery discharge coming out like a period but with no odour at all. He claims he pulled out before ejaculation. I have been on the pill for 3 years but took 2 antibiotics (Amoxicilin) yesterday but stopped taking them. After the second time, the itching has stopped and there is still no smell. It burns to urinate and there is so much watery discharge. What could this be? What are the chances of me being pregnant? If i took the morning after pill, would it still stop it from the first time we had sex 4 days ago?