How to know if I bought Minecraft?

It does not say on my card I have payed yet and does not let me sign in with then name I picked but if I try to buy it again with the same name again it tells me the name is in use. Also, after I payed for it it told me it could take up to a couple days to confirm it depending on what payment method I choose after I clicked buy Minecraft again but I pressed refresh and it was gone and had all the buy Minecraft options and that's when I tried to buy again but told me the name was taken.

It actually takes a while to "get" your minicraft account. I had to wait a few days for it to be registered. I bought it through the Internet and it takes about 5-7 days. It probably takes a while because they receive many other letters.