Hi Sue, sorry to take a while to respond, but I hope you're doing ok!
Often I think that raising the question poses more of an answer than you realise. If your career was fulfilling, you rarely feel the need to think 'hey time to change!" right?
I understand the need to take calculated risks - as adults we are very rarely without commitments and financial responsibilities that may dampen the risks we're willing to make in the pursuit of a more fulfilling road.
I would suggest having a good meditative think on the things that are important to you. Are you motivated by money? Can you move forward with less? Does your job give you the work life balance you want? Are you drained when you leave work? When are you energised? What makes you happy? What's your 6 month plan? 12 month? Where do you want to be in 2 years?
These sorts of questions really helped me to find my path, and that's not so say that either journey will be easy, but just have the courage to make a leap either way.
Lots of hugs and let us know how you're going :D