How do you know your milk supply is drying up?

My twelve month old is exclusively breastfed, feeds maybe 4-6 times a day depending on how needy she is from day to day. This last week she has become increasingly figitty on the boob and grunting like she’s frustrated, pulling off and going back on. It’s just very out of character and i don’t know if maybe she’s not getting enough milk. When she comes off I squeeze and normally milk will squirt out but while some milk does come out, it’s more like little droplets on my nipple and not squirting out.

Is my milk supply drying up? How do I know?