HELP!2 Month Old has 15 plus diapers a day?

My now two month old son goes through 15-20 diapers a day!it has lowly gotten to be more and more each week he grows. Now he has only one or two poos a day, healthy looking formula fed poops. but every time he even barely tinkles in his nappy he demands to be changed. I kept count yesterday and there was a whopping total of 17 from 8am-11pm. Some are heavily soiled and some barely had any pee at all (you can hardly tell its been used) but either way this seems like alot!!His doctors appt is next tuesday is it okay to wait until then and ask the doctor?Someone told me something is terribly wrong with him using so many diapers and im so worried now.We don't have much money and its hard for us to buy diapers as often as we do for him, and there are no charities or diaper banks in our area of Florida (Melbourne/Orlando) that have diaper help unfortunately. someone please reply with your story or advice!thank you all :)