Hi, I am suffering from very bad depression and anxiety and have been to 3 doctors but not being taken seriously because of my age. What next?

Keep looking. Ask around get help from your doc, your minister, etc and find a doc who takes you seriously.
See Psychiatrist. See a board certified psychiatrist. If you don't get help, continue to seek one who takes interest in your condition. Try a psychiatrist at a tertiary care medical center if you are able. I don't know your age or your problem. The doctor you have seen may be giving you the right answer. You may have problems other than depression.
Need psychiatrist. I'm sorry to hear of not being taken seriously. I don't know whether any of the 3 doctors you've seen are psychiatrists, but a psychiatrist would be the most qualified to evaluate your problems and work with you on them. Please don't lose hope -- persist until finding a referral who listens to you. Rates of depression and anxiety are very high in your age group. Good ideas from others here too.