Is it possible to conceive only 2 weeks after MC and hcg above 5?

[MizezWaters]

I was between 6-8 wks pregnant when I started spotting. Multiple hcg tests were done and my hcg actually fluctuated and ended in a miscarriage that was evident on 10/31. I bled for about the first week of November with the last few days being just spotting. I went back for my follow up on 11/15 and thought I had already felt ovulation twinges the day or so before, with the telltale mucus discharge. The doc said it wasn't possible because my hcg was still at 15. I was advised to wait for my menstrual cycle twice before we tried again. After being told I couldn't get pregnant until it reached 0, we weren't worried about using any protection or birth control right then. On 11/25, I thought I had started my period, but it didn't last the typical 3 days. It was just 1 day and light. At this point, I feel like my hcg level and even a home pregnancy test would be useless since I'm so close to my miscarriage. Home test positive could be previous hcg or new pregnancy, negative could be just too early for new pregnancy (if it was implantation spotting) and hcg elevation could be from previous or new pregnancy, and low could be just too early for new. What a roller coaster! I'm 42, about to be 43, and eager to conceive since my biological clock is more of a time bomb, but I'm worried conceiving this soon will just be another miscarriage and delay future attempts even further.