Your lack of experience concerns me too but having said that I didn't realize what a well fitting bike was until I got a custom frame. I went through 4 road bikes before I went custom. I spent a lot of money changing stems, handlebars, and a couple of forks, to get a better fit and more comfortable ride.

Granted, I haven't demoed any stock frames since I bought my Serotta 6 years ago. No need to, I have the best fitting bike and components, for me. Little things like the head tube height and seat tube angle were designed for my physical measurements. Campy components, handlebars, seat post, brakes, etc. were chosen specifically for me, by me and my fitter. Even my custom wheels were built with my 105 lbs in mind. I can't think of any of the components, maybe the seatpost, that I have on my bike that would be found on a stock frame. Even my Specialized Ruby saddle would not be there in my size.

The only thing I changed on my custom frame was the saddle, I went from a WTB saddle to a Specialized Ruby. The Ruby is much smaller and a better fit.

My Serotta is the bike I ride the most. I use my stock frame on my trainer and as a backup bike.

I'm not trying to convince you to do custom, maybe you do need to have a stock frame. I went through a lot of agony before I went custom. Today's bikes are better in fit for small riders than they were 6 yrs ago but I doubt if I'd be willing to go back.