I know I think its my current boyfriends too only because if you count back 7 weeks from aug 11th its june 29th and we had sex that day which makes me think we could of concieved very end of june but i could be wrong and yes it would cause horrible problems..
But then if you put your due date as March 31st then you've had to have sex from 7/3-7/8.. If your due date is still March 31st then I would say that the baby is your current boyfriends, hopefully that helps a little bit.
I would say ur current bf is the daddy. There's is probably a one in a billion chance the other guys is if ur sorry is accurate. And if I figure back to my actual day of conception by how many weeks and days I am, it puts me at July 16th, but this I'm expecting app says it would have been July 30th which I find false cause I know when my fertile week was. So idk what the app goes off but I'm sure if u count back exactly, it will tell you Dam near the right day u conceived and from there you may be able to know for a fact it was ur current bf. Don't let him know ur doubting it tho. That can cause HUGE issues!!
I went on this website http://www.babymed.com/pregnancy-due-date-calculator?event=0&cycle_length=28&weeks=5&days=0&ivf_days=3&MM=6&DD=8&YYYY=2013&showResults=1 and if your period was last on June 8th, then the sex for getting pregnant was from 6/17-6/22.
i would get a DNA test if you have the money after the baby is born, your boyfriend might be upset but if you explain the situation he MAY understand, but if the other guy is the father and doesn't do anything for the child, get child support on his *** lol but good luck and hopefully things work out for you like you want, and it is slim but possible to get pregnant by pre c.u.m or just a small amount.