TTC after miscarriage

Need some help Ladies!I'm 27 years old I had a miscarriage last month with my first pregnancy ' I was 6 weeks.i used OPT 10 days after my miscarriage and got no smiley I then used it again on day 13 and got a smiley face.im getting slight cramps in my lower back and stomach now and again , i also feel tugging in my stomach im getting real sore head on and off.im on 12dpo but I'm getting BFN WITH first response 😏😏 I really don't know what's going on am I testing too early or is there no luck this month😢