Spotting/Bleeding 4-6 DPO while TTC after D&C

LL
I had a missed miscarriage at 11 weeks in Jan 2017 with a D&C.  The D&C was Jan 19 and my period returned 29 days later on Feb 17.  Between that time I had lots of bleeding and spotting off and on.  To the point where I went back to the doc for another ultrasound to confirm everything was removed.  The Ultrasound showed a small amount of fluid, but they said it likely was just some leftover blood - nothing from the pregnancy was left.  
My period was heavy/med flow for 5 days like it was before I got pregnant, but then I spotted for 6 days after it 'ended.'  My husband and I felt ready to try again so we BD'd during the fertile window.  I'm 6 DPO and have been spotting bright red blood off and on since Fri night  (4 DPO).  Yesterday (5DPO) the spotting was accompanied by some pretty bad cramping.  Today some very mild twinges, but no cramping really.  I'm sure of when I O'd because I used clear blue digital opk.  I had 5 days of flashing smiley and 1 day of solid smiley on CD17. Before I got pregnant I was usually O'ing on CD17-18.  The blood is like a gush of bright red and then it's light pink the rest of the day.
I've NEVER spotted mid-cycle before.  I was on the pill for a long time, but when I got off my period was super regular - 29/30 days every cycle.
Anyone have any thoughts?  Is it possible to develop low progesterone after a D&C or MMC?  Is my body just still adjusting after the MC?  If it keeps up I will probably call my doctor.  I'm scared to work out or have sex or do anything to strenuous.  And it's making me feel crazy.  If by some miracle this is our rainbow baby I don't want to do anything to hurt, but if it's not I want to know what's up!  Help!