Welcome mulb222!! This is a wonderful site for many issues.
Sorry you're in such a predicament.
You have listed many, many reasons why you are so hesitant about this upcoming marriage.
Do you think she would be surprised/hurt if she knew how you really feel, or have you two already discussed these things?
If you "think" you should call off this wedding, well... go with your gut.
Trust me, from personal experience, calling off a wedding is a lot easier than a potentially messy divorce.
Marriage or not, I personally think pro golf sounds great.
You are young, lots to think about, lots of life yet to live.

Best wishes on your decision.