I think its for ur bf but dont count me on it... sperm live.up to 5 days so since.you say the ex didnt *** its a higher chance its ur bf and this app can tell you when you conceive it that helps any..
but only way for sure is to get a dna test
Even though your ex did not ejaculate, there is still a possibility of sperm escaping. Luckily for you, usually you ovulate approx 2 wks after the first day of your period, which means you can conceive around those days. DNA test is your only choice to confirm it
People will tell you that being on your period is no guarantee of contraception. That would be true if you were at day 4 of bleeding, and the sperm swam up into your tubes, and you ovulated on day 8 (a bit early in the cycle according to average). It is not usual for women not to ovulate precisely at the mid-point of their cycle, so the scenario above can apparently happen, and women hear about this and repeat to each other the blanket statement that you can get pregnant during your period.
But you said you had sex with your ex on the *first* day of your period. Frankly, two days before and one day before your period comes, and the first day of the flow, are about the least likely days of your cycle that you could get pregnant. You simply will not have gone through a follicular cycle yet. Even if he had some sperm in his pre-ejaculate and the sperm lived a while in your system, it is far less likely that he would be the father than someone you had sex with later in your cycle and who ejaculated.
Getting an ultrasound in your seventh week (counted from day 1 of bleeding of your last period) would be helpful to back this notion up. They will tell you an estimated due date, which is based on the measurements of the baby. You can plug this date into a conception calculator online and work out the most likely date of ovulation. If the most likely date comes up August 14 or so, you can stop worrying so hard about July 29.