Unwanted pregnancy. This nausea happen?

Me and gf have sex in 18/1/18 with condom...but in 29/1/18 we have unprotected anal sex....after that i gave her unwanted 72 within 1 hour...after taking the pill she have heavy bleeding after 7 days... after that My gf have periods in 15/3/18..and the periods was normal in flow, amount and colour...and we done beta HCG test in 29/02/18...and result comes 0.48 mIU/ml...what is the result means negative or positive? After that she have nausea when she eat...but the nausea was not many time in a day...its happen one time in 30/3/18...and one time in 31/3/18...it's means two times in a two days... without this nausea she was not having any pregnancy symptom...can this nausea happen for pregnancy? And my gf have some liver problem...so why this nausea happen? Pls tell me...I am very tensed...