Smear tests didn’t pick up cell changes!

So I got referred for a colposcopy after symptoms and an abnormal looking cervix on examination from my doctor. It was an emergency appointment and have been seen today. I had cysts which are normal and erosion which also can be normal BUT I had a lot of white looking stuff when they put the liquid on my cervix. I had a smear late last year so really not that long ago and the doctor said it was interesting the smear didn't show anything as I probably have high grade! I have to now wait for biopsy's to confirm it. 

the thing that gets me worried is that my smear was clear! And if I have to rely on smears as a treatment for low grade how can I relax and trust it!