I have asthma in my early 20s. how likely is it that i also could have gerd?

GERD: Your chances of gerd are about the same as everyone else. Try some maalox or other ant acids especially at night. Continued discomfort needs assesment by your family dr.

Slightly higher: I would actually say your chances are slightly higher with a concurrent history of asthma. It is well known that gerd can trigger asthma symptoms, so the fact that you have asthma places you at a slightly higher risk of having gerd. If you're having abdominal pain after eating, wet burps or other concerns, i'd let your doctor know!