IMHO - don't stress about this. A lot of riders are 50+ and on the Clyde or Athena side. We ride because it makes us feel good. The Trek 1.2 is nice; we got my son one last season- which he rode about 1500 km including a sagged tour. The bike performed well- his is an XS with 650c tires, hope he hasn't outgrown it for this season. But you might want to check out a flat bar style road bike - like the Specalized Vita [Trek has at least a couple models - don't know their designation] Slightly fatter tires and more relaxed riding position might be a better place to start & feel better, yet provide some nice performance.
ps - perhaps a Sirrus instead of Vita - the Vita might be a women specific design - get what ever fits and feels better.