I would suggest the ovulation predictor kits sold at the drug store to tell you when the best days to baby dance is. It is really easy to use and inexpensive. You could also see your dr for a semen analysis and maybe get started on something like clomid to help increase your chances. Good luck to you both
Ginger
OK, you're 21, not married, and you want to have and raise a child together. This obviously means you are well financially set and have committed to be together for the life of the child or at least the child's first 18 to 21 years, and have a good job that you don't think will fail you, and she is also working [or else you are earning enough to cover the family], and you have both completed all the education you need and have a nice place of your own to live. Given that, have you gone to talk to a doctor to be sure the timing of the sex is correct in terms of when she ovulates? If not, go do so, maybe your timing or something else easy to correct is the problem. If you have done all of that, go see a fertility doctor and get a sperm test for you and hormone testing for her.