It's normal to feel a little bit depressed when your expectations do not match reality. I think it's important to stay strong, don't be discouraged.

Keeping yourself motivated can be quite tricky, it takes a lot of determination and support from others, so it's great that you're opening up about your problems on this forum. Although I can't really help you with your problem (maybe you're exercising too much and your muscle mass is rapidly increasing) I can share some tips about staying motivated, from my personal experience with weight loss.

Always award yourself a little gift after each week of dieting (if you decide to start a diet). It could be your favorite piece of pie (a small piece of course), or a book, a bracelet, a little something to put a smile upon your face. Avoid anything that can make you feel guilty afterwords though.

Stop weighting yourself too often, because you'll end up obsessing over a number, and that's not good. Use a quantum scale (you should be able to find one online), it does not display your weight it simply records it and lets you know when your weight starts changing again.

Another thing I found motivating is buying clothes a few sizes smaller. I was so eager to fit into those clothes that I actually stuck to my diet.
Talking to other people who are going through the same things you are is also great for your morale.

Most important of all, don't obsess too much about your body image and keep a positive attitude.

Good luck and I hope this helped.