I'd like to join Sophie_M in welcming you here. She gives good advice.
Crying is never for no reason, and while you may not be exactly sure of why you cry I guess there is one thing you can be sure of. Life can be so much better, to feel happy and appreciated is the normal state of affairs for most people. Unfortunately your parents, even with the best of intentions, are saying exactly the things that will trigger you.
Having "nothing to cry about" is just plain silly, you do cry, there has to be a reason. The fact your parents can't imagine it seemly means lack of experience on their part - and therefore no understanding. It is NOT a reflection on you.
You did say "I feel like I can’t be myself anymore, it’s as if my parents are holding me back from being who I really am". Do you think you could say more about who you want to be, who yourself is now"? It can help us understand the problems you face.
Life can be hard and not surprisingly you retreat, into your room. Many people do this, a reaction that while it does give some peace for a while does not help in the long term - it leaves you on your own with nothing or nobody to make matters better. It also has the unfortunate effect of being seen as 'unproductive', again a judgment you do not deserve.
I can understand others as seeing you as happy and joyful, in my own case it was a mask I put on, it stopped awkward questions and let me be with people in the ordinary way. Again in the long term an isolating and unhelpful response.
I would very much go along wiht Sophie's suggestions, first do you have a sibling or freind you can talk things over with frankly , someone who just listens and cares. Trying to face all this on your own is horrible.
Secondly getting some advice would be exactly right, and phone or web-chat to the Kids Helpline can get you started. They are used to these situations and make suggestions that can work. You can talk to them more than once without having to explain it all over again
I'd really like it if you came back and talked more