Thanks. Appreciate the advice and I think you hit the nail on the head about needing more of the strength work, longer intervals and continious tempos. I am going to try and transition in that direction. Pretty much like in this arcticle from McMillan:
https://www.mcmillanrunning.com/time-to-rethink-your-marathon-training-program/
Regarding side stitches, I don't think they are anything serious, I mostly get them in faster races/TTs when I overcook myself/eat too much lactate for my current fitness. Wikipedia says if otherwise healthy they are not a concern, but of course they are very annoying as they are ruining races. If I get to talk to a sports doctor, I will ask about them, but general practitioner - I don't really see the point.