What age should my child stop using the bottle? Mine is 19the months old and only gets bottle for milk at naptime and bedtime. I am starting to wean.

Stop the milk. I think a baby can carry around a bottle like a prize friend for the first few yrs.But that is only if the milk or other sugary feeds are replaced by water. Save the milk for a cup where it rolls off the tongue into the throat & doesn't sit around the teeth feeding germs that rot the teeth. The kid can fuss a bit with the change but if they still want the bottle it wont lead to problems.
The American Academy. of Pediatrics recommends weaning as close to 1 year as possible, limiting milk & milk products to 16-21 oz./day from a cup. See a pediatric dentist to rule out cavities. Read, cuddle, brush his teeth, then put him in his bed drowsy, but awake to learn to self-calm for sleep. His protests will worsen at 1st, then stop if you consistently ignore them.See healthychildren.org for graded ignoring.