IMO, you’re probably doing nothing wrong. If you sit down and make a budget it’ll give you a clearer idea of where exactly you money is going, but to put it simply, things cost money. Once you knock off tuition, mortgage, insurance, you probably aren’t left with too much. If possible, pay your cc bill every month (or avoid them altogether unless your doing well with rewards). Do you do shop at Costco? If it makes sense for you (meaning you will actually use the stuff before it goes bad), go for it. Does your checking account have a service fee or a charge per debit card purchase? Are you going over cell phone minutes/texts/data usage? Basically just know where your money is going before it goes there.
Hatzlacha