Oh dear! I hope the ending you get is worth all this stress!
The walkthrough is coming, but if you want something Leo-specific just to ensure you're on the right track, email me at support@blackcross-taylor.com and I can give you some feedback without any worries for spoilers.
(Just adding here - you sound like you're on the right track to me. There is a decision coming up - just pick the option where you don't actively work against Leo and you should be fine going forward)
Hope you have fun with Mathys, at least ^_^