Could I be pregnant??

I haven't used any birth control for the past 6 months. On Dec my period was normal. I usually get my period the last days of the month to the first days of the next month. January I didn't get my period & Feb I got it for 4 days witch it's not normal & it was mostly spotting. I still haven't gotten my period this month. I took 3 pregnancy test & they came out positive. Within 3 days later I took another pregnancy test and it came out negative. What do I do? I'm confused.