22dpo- need advice for peace of mind

I miscarried in October at 8 weeks. I got pregnant again in January and am currently 22dpo. I took a frer today and the test line is not getting anymore darker? Should i be worried? My breasts are not anymore tender. But i still have some lower back pain and some dull cramps on and off.

I went for an ultrasound 3 days ago and all they could see was a gestational sac. I will go for a second ultrasound at 7 weeks to check if there is a heartbeat.

Perhaps i am overdoing it but would like to hear your views