In the past i always brushed my teeth too hard. one part of my gum just above one tooth is up higher, is there any way to fix this?

Yes: Depending upon the severity and the true cause (it may not be from over-brushing), this may be easily fixed. The kind of dentist who most commonly addresses this type of problem is called a periodontist. Your general dentist should be able to recommend one in your area.

Tissue graft: A periodontist can cover the root with a plastic surgery procedure to graft over the exposed root. Find a periodontist.

Maybe: First of all, use a soft bristled toothbrush, this will help to not scrub your gums away with vigorous technique. Depending upon the root and boney architecture of the area, a gum graft may be an option. Sometimes, contouring the neighboring gum tissue to match is an option, but may not be in your case. Seek an opinion from a periodontist to see what your options are.

Gingival graft: A periodontist is they way to go. They can often times do a gum grafting procedure to cover exposed recession areas!

Yes: Gum graft surgery can fix this. But before you do this you may want to evaluate if the tooth is too forwards. Orthodontics may be needed to reposition the tooth to create a favorable situation for success long therm.

Yes: Be sure that it is actually loss of tissue and not the normal architecture of your gum line. Typically canine teeth have a gum line that is higher up, so it could be normal (and you are just 18). Look for a change in color from enamel (white) to darker area called cementum which is part of the root, in that case it is eroded, and should be evaluated by a periodontist who may graft the area.

Gum Recession: Teeth came in pairs. The two upper front teeth called central incisors should have the same gingival level. That goes too for laterals and the eye teeth, . If there's malocclusion, interference is very common. A combination of deep bite, improper interdigitation, plus parafunctional habit like bruxism (grinding ), cannot only cause gum recession but abfraction cavities on both front and back teeth.