Hello again!
Take what I'm saying with a grain of salt because ANYthing is possible... but from a generalized facts based on the majority here's the facts ma'am

lol!!!
Ya it is definitly possible to be pregnant, but it is very early and that would put you at approx 8, maybe 9dpo... the LH surge doesn't mean you ovulated that day just that within 24-48hr period on the 23rd from that + OPK. If I were you I would wait a few days and test with a FRER (first response early response pg test) in the am. If you get a positive, shoot do a digi too!
Also, implantation generally takes place 7-10, even up to 12-14dpo!
Do you temp/chart? That can also help show you when you O'd & pg by the temp fluctuations.
It's best to wait until 14dpo, but allot of POAS'aholics start earlier... but it's a very very small percentage that actually get a positive on 9,10dpo.
So hold out a couple, 3, 4, days and try testing again... that might give you more definitive answers.
Generally a line is a line and means you're pg.... unless it's one of the dollar store cheapies, those don't have the best reputation as they a famous for their evap lines.

with Kary too... yep, good point! Did you ever get bloodwork showing your levels zeroed out after your mc?