Hi! Just FYI they can NOT require you to cut your hair as long as you are within regulation. I am also prior service Marine Corps, but it falls under the department of the Navy and we have the same grooming policies. Here is a quote DIRECTLY from the navy regulation:
"b. Women. Hairstyles shall not be outrageously multicolored or faddish, to include shaved portions of the scalp (other than the neckline), or have designs cut or braided into the hair. Hair coloring must look natural and complement the individual. Haircuts and styles shall present a balanced appearance. Lopsided and extremely asymmetrical styles are not authorized. Ponytails, pigtails, widely spaced individual hanging locks, and braids which protrude from the head, are not authorized. Multiple braids are authorized. Braided hairstyles shall be conservative and conform to the guidelines listed herein. When a hairstyle of multiple braids is worn, braids shall be of uniform dimension, small in diameter (approx. 1/4 inch), and tightly interwoven to present a neat, professional, well groomed appearance. Foreign material (i.e., beads, decorative items) shall not be braided into the hair. Short hair may be braided in symmetrical fore and aft rows (corn rowing) which minimize scalp exposure. Corn row ends shall not protrude from the head, and shall be secured only with inconspicuous rubber bands that match the color of the hair. Appropriateness of a hairstyle shall also be judged by its appearance when headgear is worn. All headgear shall fit snugly and comfortably around the largest part of the head without distortion or excessive gaps. Hair shall not show from under the front of the brim of the combination hat, garrison, or command ball caps. Hairstyles which do not allow headgear to be worn in this manner, or which interfere with the proper wear of protective masks or equipment are prohibited. When in uniform, the hair may touch, but not fall below a horizontal line level with the lower edge of the back of the collar. With jumper uniforms, hair may extend a maximum of 1-1/2 inches below the top of the jumper collar. Long hair, including braids, which fall below the lower edge of the collar shall be neatly and inconspicuously fastened, pinned, or secured to the head. No portion of the bulk of the hair as measured from the scalp will exceed approximately 2 inches. <Figure 2-2-2> refers. A maximum of two small barrettes/combs/ clips, similar to hair color, may be used in the hair. Additional bobby pins or rubber bands matching hair color may be used to hold hair in place, if necessary. Fabric elastics and colored rubber bands/pins are not authorized. Hair ornaments shall not present a safety or FOD (Foreign Object Damage) hazard. Hair nets shall not be worn unless authorized for a specific type of duty."
Here is a link to the infomation:
http://buperscd.technology.navy.mil/bup_updt/508/unireg/chapter2/CHAPTER_2.htm.