Just to be clear, I am not advocating doing anything illegal here but....
When I was between 14-18 I would buy .22lr ammo online and have it shipped to my house. Back then you were asked to input your birthday but there was no way for the selling company to know. Then when it arrived to your house via UPS, they were suppose to have someone of proper age sign for it, but they never did.
Of course I understand that this will probably not work out for you because things have probably changed in the last ten years and it only worked in the first place if you have a credit card, something most that age do not. All I am saying is you can find almost anything online including powder, it just depends on how much you are willing to pay.
Practice doesn't make perfect, it make permanent.
When I hear a Liberal say "I can speak for gun owners because I own a shotgun" I just want to scream "Well I can speak for vegetarians because I like lettuce on my cheeseburger!"