Simple, been there before. I call it the "Four Step" career turn. - First pick a language you like, that could land you the kind of job you want and STICK to it. - Second, practice, write a few complete apps - Try to get any type of "paid" work that involved coding in that particular language... I recommend consulting...freelance. - Now you have a credible portfolio, finding a pretty serious Software engineering position in ur desired domain should no longer be a problem.

The whole process should take about year or less. And no you're not in a hole. If you know ur stuff u'll get noticed. Besides an addition to ur new knowledge u'll have 4 year of SAP ...nothing to sneeze at. For some companies that may just be the perfect mix. Personal bias (I recomend PHP)