Hiya Pat

I think you have answered most of your worries regarding your fiances loyalty and sincerity by all the positive insight into how you feel about her and vice versa.

I too was worried about the age gap between myself and my beautiful wife but here we are nearly 2 years later both happy as can be with our son to boot.

One bit of advice from me is to use your gut instinct and reminisce from all the times you spent together how you felt at that time, how happy you both were/are and go from there, if she makes you happy and you make her happy then forget whats happened in the past and go for it good luck.