I feel like my parents should be able to tell their own child is going through something, but they don't see it. I've never felt comfortable sharing my feelings. How can I help myself without them?

You could try keeping all your feelings inside a journal, everyday. Giving yourself at least 5 minutes a day to release any feelings that you want to let out. Also, you can write them a letter if telling them is too uncomfortable. Something that has helped me is sharing my feelings with the ones that I'm more close to, or writing in my journal, or even speaking online, anonymously. Getting out your feelings help tremendously , especially when it comes to our mental health. Something to keep in mind is that there are plenty of listeners that can be here for you.