You will go to recruit training just like everybody else. The powers that be will most likely have you eating more than the other boots do. After a time they will evaluate your progress and act on your case. I had a friend in recruit training that looked like a qtip with red hair. The guy was about 5'6'' and did not weigh 125 soaking wet and after eating a whale. He ended up being the Platoon Honor Man.
The most important thing is not to quit. If you feel like quitting sometimes do not give in to the idea. The USMC is 180,000 people who did not quit.