I mean, Frosthaven isn't going to run away so take your time and enjoy the content you already have. Absolutely nothing wrong with that!
My group managed to unlock all of the classes (including youknowwho) and we played each at least once with the curious exception of the Tinkerer.

I'd love to give Crimson Scales and Trail of Ashes a go but we are looking to start Frosthaven with the group and I'll likely embark upon all five cycles of AT:O solo in a few weeks.