What is a normal endometrial lining?

I had an ultrasound done last week. I should have been 8.5 weeks pregnant but I knew I was miscarrying. The tech couldn’t find anything. Not a sac, no baby, nothing. Although I passed the baby and sac about one hr after the ultrasound. One thing my doctor told me was that my lining was really thick, 33 mm. Is this normal during a miscarriage? Everything online is so confusing. And although I did bleed for a few days, I sure didn’t pass a lot of clots that would make me think the whole thick lining was shed. Does anyone have any insight or experience with this? I really want to try again but if thick lining isn’t good for pregnancy than I know I need to wait.