Can babies of any age have a reflux problem? i told my daughters dr about her vomiting after eating. she's breastfed & he says since she gained weight it's her overeating & reflux is not possible? she's 2 months?

Reflux is a natural event and can occur at any age. Reflux as a disorder occurs when there are symptoms that cause symptoms like pain/fussiness at that age. Small infants go through a transition period where they get better at holding their feeds in their stomach. They have no social taboo against big wet burps. I don't consider what you describe as worrisome.