Mom again after 18 years

Help! I’m 39 and had a miscarriage in Dec. 2020. I am now 5 weeks and 6 days. My hcg level was 745 at 4 weeks, then 5875 exactly 6 days later. Then 2 days after that it only went up to 6629...within those 48 hours I had exercised a bit and had sex...then a drop of red blood, and clumpy dark discharge in the toilet a few hours later. After the 6629 result came out the OB/GYN said to come in this Monday for ultrasound and I am a nervous wreck! Am I having another miscarriage? My breasts are tender off and on, I’m still feeling bloated and gaseous...i don’t even remember feeling pregnant with my two daughters 18 and 20 years ago! I need peace of mind or be mentally and emotionally prepared to hear bad news... I’m still getting dark discharge but only when I strain...no clots, no period like blood...