Period post miscarriage

My husband and I are Active Duty Navy (he got out a few months ago). When he returned from deployment on February 16, we conceived that next week. Unfortunately, early May, we miscarried. It was devastating. I bled from May 2-9, passing the baby on the 4th. My doctor told me since everything happened naturally (no D&C, no pills), I should have a period within 4 weeks from when I started bleeding. They told me when I began miscarrying my hCg was super low and they expected it to be at zero soon. On May 13, I took a pregnancy test and it was negative. Fast forward to today.... Still no period. It's Navy medical (super slow) and I can't get an appointment until early July. I took a pregnancy test around 4pm yesterday and it was negative. My husband and I aren't necessarily TRYING again so soon but, we aren't doing anything to prevent it. We began having sex again the day I stopped bleeding (I was emotional and craved some sort of affection) and generally have sex every other day or so; sometimes more, sometimes less. Should I be concerned? Has anyone else experienced this?