Could the tests be wrong and i am pregnant?

this mite sound like a stupid question but im serious, about 19 weeksago i had a light period thastwasnt normal for me, so a week later i did a test it was neg, then i started to have symptoms so i did a nother test it was neg, so then 4 weeks later i had another light period so i wnt to my doc, she did a urnie test it was neg but by then i my were bigger my were bigger and i had all these blue veins showing up over my chest, my s arent sore tho, about a month ago i went bak and had a bloodetst it was negative but i am still having these symptoms, could i be pregnant and not no? or am i paranoid, i was on the pill and used condoms by theway, but i wasnt taking the pill properly