Am I Pregnant

I had sex in jan.On the 12th th day I was suppossed to start I was spottin a lil bit before that day and after I had sex blood came on out but it was spottin until the 16th and then I came on heavy until the 21st. I came on like normal in february. Then I had sex on the 1st of march but didnt come on till the 19th and I normally come on on the same day each month and my cycle isnt just heavy like normal either is somethin wrong or am I just paranoid.