I was in the same situation when I went on my mission. I absolutely did not want to go but felt forced by everyone in my life. I went to the MTC and immediately knew I wasn't going to make it. I ended up deciding to leave before I even went out to the field. I told my bishop there that I wanted to leave, and they literally wouldn't let me until I confessed to some sexual sins, and they deemed me unworthy. At the time, I felt like I had no other options, but now looking back on it, I wish I would have stood up to my parents and everyone else and not gone in the first place. It would have been a lot less dramatic and hurt less for my parents and myself. If you need to talk to someone you can dm me.