Pregnant but not sure it’s mine…

Patient: Hi..I’m in a fix right now. Need some answers. Had sex with a girl late last year (Dec 22), she used prostinor 2 and complained about stomach upsets and she saw some blood discharges, later she was ok. We had sex again on 6th,7th and 8th of January this year being protected once in those 3 days. She took the prostinor again, saw little discharges and later she had her period. We had it again on the 17th and 18th of February. I was protected the first day and the first part of the second day. I was unprotected the second time we had it the second day (18th) but i’m pretty sure I did not ejaculate into her. She took the prostinor a week later after she said she forgot to use it. Now she claims she is pregnant for me.I said ok but now I think something is off. She had a scan done and it says the baby is 16weeks old as of May 24. Now i’m a little alarmed, I dont want to be tricked into something that isn’t mine even though i do care about this girl. I’ve done the maths but the dates just don’t tally. I do insist on being protected all the time but she says she likes it better if we are not. I’m a little confused here, thats why i looked you up and I think you can helpIf its mine, i would take responsibility but i’m not sure if its even mine. I also did some little research. Learnt that the sperm could survive for up to 3 days in the uterus and that the woman could only get preggy on just fourteen days of the month. When I factor in all the possibilities, it still doesn’t add up. Please advice. Want to know if i should start paying child support…just saying.Thanks.

Symptoms: pregnant