If i have osteogenesis imperfecta but my girlfriend is a healthy 22 year old what are the chances of our baby having osteogenesis imperfecta?

You should see a GC: Formal genetic counseling is a good idea in your scenario. Oi is an autosomal dominant disease, which means if you have it, your child has a 50% chance of having it as well.

About 50%: Most cases of oi are thought to be transmitted via an autosomal dominant mode of transmission. That means if one parent has it, 50% of the kids will have it. To better understand this concept, look up "mendelian genetic transmission" in google.