ML do have big O!
From experience it normally has to be Daty -
Some of the tell tale signs are ;
Spasms - legs flaring uncontrollably or clamping onto ur head. Then to check if they had a an orgasm you can try to keep going even harder and faster and they will push your head away cos they are too sensitive.
To give her multiples (providing shes receptive) you can blow on her clit pussy for a short while or kiss around her inner thighs and start again slowly and go with her rhythm .
Pussy language - they will gyrate or move their pussy up and down against your mouth and tongue and hold your head if they are really into it. and like to lock hands when they are about to cum.
engorged wet pussy that opens up, dilated and a squidgy ball forms about 2 inches in that has a texture of a walnut.