Hi, Welcome to Health care magic forum.
As you describe, your growth started at 16, and by 18 you have gained 7 inches, means the growth points at the end of the bones must be active, at least to some extent.
I advise you to consult an orthopedic surgeon. You may need to have
X ray of the ends of the long bones, if they are active, you can try to have increase, to some extent.
I usually prescribe to my patient with such symptoms injections of anabolic
steroids, periodically.
Protein supplements like complain, calcium, iron, and multivitamins.
Take more of green leafy vegetables, pulses, sprouts, and protein rich foods to have early result.
Wishing for a quick and complete recovery. Thank you.