Confused and frustrated

Hi ladies, I need some advise. I had a miscarriage with DNC in February and the methotrexate shot a week later. I had my first cycle after that on 4/5/17. I had a BFP on 4/21, I spotted for a week and was bloated for another two weeks but no other symptoms. I had my first blood HCG test on 5/4 the level was 70 and then a 2nd one on 5/15 then the level was 4. Every test I have taken after that have been negative. Still haven't had AF as of yet. I still have slight cramping. Not sure what to the Dr keeps asking me to take another BFF but it's a hassle each time to find a vein so I don't want to keep doing it. Any suggestions or has anyone gone thru anything similar?