No Worries, basically the game is a puzzle type of game, and the money aspect is very tricky.
I did not change anything in Chapter 6.
Chapter 1 to 4, You can not mess up.
There is no money to speak of, and you can always recover from mistakes made in previous chapters.
From Chapter 5 onwards, you need to look after your money. There is too little money to do everything, so you need to decide where to spend your money. I tried to make it a bit easier, by throwing in some extra money.
From Chapter 6 onwards, decisions in your previous chapters will start to catch up with you and also the game forces you between a couple of paths. That's why I did a mini WT for Ch 6-7.
I made sure my logic will allow you to complete all chapters, despite what you have done in previous chapters, so it will never be in an unwinnable situation for main missions. However, for the girls other then each main mission, you could easily block yourself out of a path, and make in unfinishable, by making wrong decisions.