Can the pregnancy test be wrong?

i used to have irregular periods for up to 6 and 7 months without seein it it started comin regular sometime last year. i am ually active i had in february but it was like 2 days after my last period and he used a condom so i doubt that i would be pregnant. however this is the last time ive seen my period. i had again in early april and now its may and im still waitin on my period. i've done 2 tests and both were negative but im worrying now because my period started to come regular so what could be the problem?? and sometimes i feel a slight pain in my tummy in the mornings , could i be pregnant i did the tests one in mid april and one in may just to be sure. what could be the problem??? plz help me im 19 and my parents would be so disappointed if i was to b pregnant caz im to b startin university in september.