I feel LONELY!

But Allah Ta'lah swt will always remember. :)

Yes, you were young when life changed dramatically for you and you were made to do all those things. May Allah Ta'lah swt reward you for your efforts, Inshallah.

You need to find ways to stay thinking positive and happy now. If you feel like crying in your room at night again - make a dua for your Mother, which she will receive and pray until you fall asleep. You are 21 now, and you will get your Masters degree by 23 - so still young! Lol. If marriage feels to early then you can continue with studies more or get a job until you feel ready. But be patient with Dad and Brother. Be proud of what you have achieved as you are such a smart student, Marshallah and you still managed to study through a difficult time.

Even though your Step-Mom and you have awkward, quiet moments together, still be patient and remain polite to her. If she doesn't make conversations or gives one-word answers than don't feel you have to keep the conversation going as it will just make you feel more awkward. Just enjoy a quiet trip in the car. Prehaps one day your Step-Mom will feel pleasure in her heart for you and the patience you always showed her. :)

Allah loves those who are patient. (A’le-Imraan 3/146)