Hey LMills,
I just wanted to chime in for support! I too have been told I shouldn't have babies because I have to take such high doses of medications and because my Crohn's is in bad shape. I can empathize with how you feel and I just want to send you all the good thoughts in the world!
I echo ivy6's comments 100% in that you should get second and third opinions about your pregnancy issue. I had to have my large intestine removed several years ago and I spoke to several physicians about the matter. Not all supported it, so had they been my primary care physicians, I may be in a very different boat right now.
As far as the steroids are concerned, there's no reason someone in your doc's office can't help you with that question. They've been using steroids for IBD for decades, someone should have some insight as to how to help you. Just remind them that they HAVE to help you! :)