[kaycee]

Well I am by no means a carpenter,but I would rip that roof off and start over using some of the 2x4 u take off.Get a piece of plywood and cut strips 3 1/2" by 1' put a piece on each side of your seam where the 2 butt end for end.Glue(liquid nail) and nail them together,keep your seam in the center of your building18' wall to wall center would be 9'.I would use new wood so your shed is 18 ' wide I would use 10' boards this would give u some over hang on each side how much u want is your call, cut em off at 18' or have a 1' overhang on each wall or what ever u want make it a 6" overhang.Then you can use your scraped wood four your pitch.I hope I made some sense here I could show u easy but this trying to explain it is my weakness.