Trouser fitting – tightness in seat and diagonal creases

Hi all,

After many months of forgetting about trousers after frustration with fitting, I have finally calmed down enough to get back into it!

First of all, a question about fit – how high into the crotch is the fork meant to go for bespoke trousers? Obviously I wouldn't want them to be uncomfortable, but is this the only consideration? Is the fit better if they are higher / more freedom of movement?!

So far I've added 3/8" at the side seam from the bottom of the pocket to the waistband. I've also experimented with the seat seam at the back, as it was giving me a bit of a ******. I was surprised to find that letting out the seam made it worse, while taking it in made it better. Don't understand at all. I let out the inlay on the topside form completely which made it more comfortable – not sure if that was the right thing to do. Anyway, here is a picture of what I mean. I checked my figuration by the way, and was pleased to find it was indeed straight leg...

This is with the trousers not sitting right up into the crotch, by the way, if that makes a difference!