Testing down hcg, do I believe this OPK?

L

I’m 4.5 weeks post miscarriage (MC at 8.5 weeks). Tests are ultra sensitive (closer to FRER sensitivity than other cheapies). 1.5 weeks ago bloods showed hcg of 40 and I stopped getting false positive OPK’s (that had been triggered by leftover hcg) about 2 days later, so just over a week ago now.

Think I can trust today’s OPK even if hcg test isn’t fully negative?