The only way to find out for sure is to go to a doctor. If you can make yourself go, it would be a great start.
At your age, the hormones are going crazy in your body, it is a time a many changes, physically, mentally, socially...ect. Keep that in mind. I would definitely get the depression checked out.
Try seeing a trapsit they won't judge you just try and find a way to help you.
Hormones play a big part in depression, especially with a teenager. Have you been to a doctor recently. You could ask your family that you would like to start having a yearly physical (good idea anyway) and talk with the dr. about your concerns. Print off the list of depression and mark off those concerns that you are having. My doctor likes me to bring a list of questions anyway. The dr. can help you see if there is anything natural you can do to help with your mood. I know you said you don't want to go to a dr. but the problem is that may be the only way you know for sure if it is a problem.