3.9 HCG via blood work

I need everyone’s help. So I’ve been getting faint pregnancy test positives since Friday, and today I finally had my blood test. Well my dr said my HCG is at 3.9 so I should be cautiously optimistic. I asked if that indicated an early miscarriage or a chemical pregnancy or what. They said they don’t know yet, it could be that I had a late implantation, and will want to retest my blood in 2 days for more information. I’m currently nervous and heartbroken because I keep getting positive tests but I feel like I’m setting myself up for heartache. Has anyone experienced anything similar and had a successful pregnancy?