How can i be pregnant with no signs?

Ok so i went to the free clinic and i had a positive pregnancy test. I didnt believe it so the next morning I bought one and took that and it was positive again. But the thing is i have irregular periods. Its may 4th today. And i havent had a period since Jan. And i just found out today.. But am i really pregnant or is it a false positive. Also no signs. just peeing alot.. but other than that i feel fine. So if i am pregnant then i have to be 3 or 4 months right? Advice. i need answers!!!!