Hi.
It sounds like your parents might be operating under the same assumption that you just put forth: They clothe you, feed you and so on, so what's the harm in asking for little money from you every now and again. But I'm guessing that part of the reason you like making your own money is the notion that you will have some degree of autonomy in spending it.
In the future, you could try opening a checking or savings account--depending on how much access you want to have to the money. Checking accounts offer more access than savings accounts. That will allow you to keep the money out of the house until you need it. Let your parent know that you are doing so.
Also, you might suggest to your parents that the family keep a "petty-cash fund" somewhere in the house for those occasions in which one of you needs cash for household items. Each working person in the household can contribute a little each week.
If neither of these solutions work for you, consider other ways in which to set some boundaries with your parents without coming across as stingy and uncaring. The trick is to strike a balance between the gesture of making contributions to these little family grocery runs and saving money for your own uses. Any pro-active gesture toward "chipping in" will probably be appreciated.
As to whether to ask for your money back, how would you feel about letting it go this time? If this is eating at you too much, perhaps you can, at least, broach the subject of the gift you received for your birthday. Let them know that you think it's unfair. After all, it was a gift.
Good luck!
