I think I'm depressed but don't want my parents to overreact or worry about me. Who should I talk to or what should I do?

Depending on your age - there are many options. There are a lot of online or by phone counsellors available to young people for free, and a multitude of online resources. beyond that, if you're old enough to visit the doctor by yourself, perhaps try chatting to your GP about it? A doctor will be able to help you work out what's going on, and may have some advice in terms of discussing how you're going with your parents. It's important to realise that getting someone to lend a hand is a fantastic step towards helping yourself - and that includes coming here!