Hello, if it is a first time sex for both of you then it is common to have minor abrasions(cuts) on penis and irritation and pain in Vagina and minor bleeding due to tearing of hymen. So no need to worry. Coming to pregnancy test,, yes it could give wrong results if not done on proper time or not properly. UPT kit strats detecting pregnancy from 21st day of her normal period cycle and most UPT tests are positive after 28th day of cycle (next period date) if she is pregnant. If test is negative after 28th day or if she gets normal menstrual bleeding then no need to worry. Next time use some condoms which avoids both pregnancy and STD'S.