TTC after miscarriage

Hi everyone, first time ever posting here. So I have a weird situation. I had a miscarriage in December 5 weeks along (if this matters). We have been ttc since then. My husband deployed very end of June. i have been taking prenatals since Dec we have been actively trying. In June we tried everyday, twice a day. Up until the 27th. We haven't had sex since (he is now deployed). on July 1st I had brown spotting... Hours later I started to bleed. I bled again on July 2nd. Then there was no more bleeding. On July 5th I had really really light pink bleeding once. And nothing happened since then.(my periods are normally 7 days minimum so this was very odd for me).  I am now long overdue for my period  it is August 5th and it still hasn't come?? I have tested twice and both have come back negative. i would be at least a month pregnant by now so I am sure it would show up on a test by now. Should I go to a doctor? Is there anyway I am pregnant? Why is period this late? 6 days late. Also, I have been exhausted!! Like completely drained. I even had to call off work the other day because I couldn't get out of bed. I've also had a faint back pain. Last week I was cramping really bad and kept thinking my period was going to come but it never did. What do I do? Thanks in advance.