Been trying to get pregnant, now I'm so tired/dizzy...?

Ok, my husband and I have been trying to have another child. I have no idea when I ovulate, my last cycle was in seven months ago when I got pregnant, but then almost two months ago lost my baby girl. We've been trying again after the doctor said it was ok, and now for a week off and on I've been feeling unusually tired, and dizzy usually in the afternoons, and then I'm fine in the mornings. I still have absolutely no sign of bleeding, and its been over a month now. The last time i did a pregnancy test it was negative, that was a week ago. It's hard to be patient, I would have had my other baby in mid-Aug this year. :'(