TTC after MC

Bria • 30 years old - Married - 20 month old

I fully passed my MC 31 days ago. I was 8 weeks but the baby stopped growing at 7 weeks. It was such a let down. Since then all I think about is getting pregnancy again. I got bloodwork done on Monday and HCG was 3... this Friday it’s at 2. I’ve been spotting lightly for about 4 days now and testing faint positives on pregnancy tests. I’m so confused on how a pregnancy test can pick up such a low HCG and why my HCG was 3 on Monday but only at 2 on Friday. I would think it would be at 0 by now. Has anyone had similar experiences and found out they were pregnant again without a period in between? Any advice or personal experiences would be amazing. I just can’t stop my mind from constantly focusing on getting pregnant. I’ve never felt so lost.