Trying to have a baby, guy?

Hi guys am 25 years old, when I was 22 my gf at that time was pregnant and she lost it after 7 weeks I blame my self for her loosing our baby, it took a year to get over that ripped me apart so bad. After we broke up i was with a diffrent gf and she had problems with her womb not being strong enough to carry and she lost 2 babies or so its ment to be believed we broke up after that. Am now 25 at a good age to have one and a good job but and seeing this girl who is great but we had sex about 10 days ago no protection and thought there would be a chance she took a test and its neg, do you think its me am i doing something wrong? and does it have to be when she is overlating dont even know what that means.