Litvishchosid- it’s true that Hashem can give you more money if you run out. I don’t know if there is a way to know how much Hashem planned to give you. Just because Hashem gives you money after you blew your salary on a fancy sports car doesn’t mean you didn’t waste the money. Maybe you are using up zchusim for that, who knows. But we don’t judge our actions based on the outcomes. We judge them based on the information we have at the time we make the decision.
It may not be so easy to know if your wasting money. If you are spending money because you are jealous if your neighbors car, house, vacation, clothes etc then that is probably a waste and worse.
Knowing if you are spending you money properly really takes a lot of introspection. Some people spend too much other’s don’t spend enough on their family or to take care of their own health for example. It could also be useful to have a Rav or chaver to help with this.