Ok I just recently took a pregnancy test and it's positive. My husband and I have unprotected sex all the time, but I had unprotected sex with my lover once too! If my ovulation date was March 17, 2014 could I have gotten pregnant by my lover, when we had sex using pull out method on March 9, 2014?

Nobody can answer this. You're playing a game here by even trying to guess and hoping for accuracy. You will need to have a DNA test done to know the answer.

The dates are too close to tell. You will need to do a DNA test after birth to make sure.

But legally, any child born to a married couple, the husband will be the legal father unless challenged.

Get a DNA test done... there is no other way of knowing for sure... you NEED to know for the kilds sake because of family medical history and susceptability to certain conditions that are inherited.

Yes it could be the lovers,
1. how do you know ovulation dates, online or phone apps are not always correct. Are you testing for this medically?

2.pull out method, allows pregnancy,

3. there is no way to tell exactly, conception dating is give or take a week (2 week window) and sometimes longer.

Its entirely possible with the little facts you have given that your lover got you pregnant. Only a DNA test can determine paternity.