Can't really help as I have had no experiece with it (although my girl should have been through that process, might have prevented the issues I am having now)
Only suggestion I can think of is go to a baby shop and try Issabella in a variety of prams to see if any work better for you.
Possibly look around for an emmulunga, they are bulky but if they are made he same as they used to be they have a lot of space in the seat section.

Good luck