Well, the thing is, your tailor should know this. If he doesn't know it, and you don't know it either, you're better off with ready to wear trousers than with bespoke.
Going bespoke without knowing much is fine if you go to a reputable tailor such as A&S or Steed or whatever. They know how something should fit, and they'll guide you with the choice of fabric and other details. You can walk in there without knowing anything about classic menswear and still end up looking good. If you go to a tailor who doesn't know this, the end result will depend entirely on you.
Besides, I'd have a hard time trusting a bespoke tailor that doesn't know how to solve fit issues, which is the main reason for the existence of bespoke tailoring in the first place. I wouldn't have accepted any of the clothes you have shown here so far, and would have demanded a remake. But then again, I probably would've avoided the whole issue by going to a tailor that knows what he's doing.
So please, stop commissioning things for a while, and wear the stuff you have right now. Read about classic menswear on SF and other good sources, educate yourself, try different combinations, see what works and what doesn't. Use that time to save up your money for one suit at a good tailor. Let him do his thing, and compare that result with your current suits.