I have taken several pregnancy test and everything has come back negative. I have all the symptoms of being pregnant but the docs aren't finding anything (military docs) what else could be the problem? I don't want to work out hard and cause myself to have a miscarriage but I don't want to not do anything and just be fat for no reason.

Have you had a blood test done or have they all been urine tests? If only urine tests, you may want to ask about having a blood test done and an ultrasound. They should do this anyway as a means to determine what other possible cause there might be for not having a period for four months.

How "hard" is working out hard? Depending on how intense the training has been, it may have been enough to alter your cycle.

Generally, if you are all ready in good condition, miscarriage would not be a concern with continued working out. However, if you were pregnant, altering your workouts, especially as the pregnancy progressed, might be necessary/wise.

If pregnancy is not the cause, it could be hormonal changes, in which they would need to test as well. Have you been on any sort of hormonal birth control? That can sometimes play a role, especially the depo provera injection.

I have had the works done. Ultrasounds, blood test all of that. I used to be on birth control but I stopped taking it because I ran out and Im overseas now so the military won't refill what works for me and since I have high blood pressure I need to stick with what works for me because the rest give me migraines. I actually just started working out again because these doctors have been very frustrating and vague and I just get upset. With my first baby my test didn't show up positive until I was 5 months and I used to be in the military now Im a dependent and they won't give an ultrasound to look for a baby unless the test comes back positive so when I had mine done they only checked my vaginal structure (lame right). I have nvere been on depo. Im going on 5 months without a period now and so far I have not gotten a response worth repeating or that satisfies or explains why I still don't have a period. Thanks for the advise though.