Good luck to you, and congratulations on your upcoming beloved child.
Thank you for your answer :) it was well informed.
I did not mean to seem to ignore that you wrote your cycles are irregular. I was saying that even if they were regular, it would be hard to be certain. But of course, if they are irregular, you could have ovulated in a time range could readily have included either guy.
I agree that if your cycles are 24 days long (and if they are regular like clockwork instead of irregular) the chances are that you ovulated around the 10th. Unfortunately for assuming the father is the guy on the 10th, sperm can live 5-6 days in your reproductive tract. This means sperm from guy A would still have been alive and viable in your system when you had sex with guy B, and presumably when you ovulated also. A possible clue will be when you find out the gender -- some science would suggest that because of the timing and the lifespan of x and y sperms, a child from the first guy would be a girl, and a child from the second guy would be a boy. But again that would be if you absolutely ovulated on the 10th, and there is no way to be sure of that, or of the reliability of that theory of gender selection either.
If it is vitally important to know before you have the baby, Ravgen and the DDC are reliable labs who can do prenatal DNA tests for purposes of determining paternity. They are very costly, however, and a lot of women decide the money is better spent on the baby. They do a DNA test (for a tenth the cost) once the baby is born. (The only times I have seen a woman write in that she is doing the prenatal test are when it literally was life and death to know.) If you do decide on a prenatal DNA test, please don't use one of the cheap so-called labs that advertise on the Internet. The ones I named above have excellent reputations, in a field that has attracted a lot of charlatans.
You'll need a DNA test if you intend to file for child support, and should use a lab certified by the courts to determine paternity. In other words, a drugstore test won't do. You will be told to use a lab where the samples are handled according to legal standards and everyone shows ID and all.
Good luck, I hope you are able to work this out without a lot of stress.
Dna thats so close together its better to know