If you were my patient, I would advise you that it is illegal for a doctor to tie your tubes without your consent, and most women on government insurance (Medicaid) are not allowed to consent unless they are over 25 or have more than two children. You probably just haven't been trying long enough. First thing to do is to make sure you are ovulating--if you are having regular periods you probably are, but you could use ovulation predictors to check and to time intercourse as well. IF you are having irregular periods, you should see your ob/gyn doctor sooner rather than later.
How can I really tell if im ovulating?