I've had problems with eyesight for 6 years. I have -1.75D for both eyes. I need 6/6 vision to join. Would Lasik help?

Actually, PRK may be a better choice for you depending upon the outcome of your evaluation by your doctor, particularly if you want to join the service.  For e.g., we recommend PRK vs. LASIK for US Navy Seals and other service men and women, depending upon the type of job that they would perform.  With PRK, since there is no flap, there is a reduced chance of flap complications among other advantages.  See the link below for info on PRK

Your level of myopia is certainly in range for laser vision correction. This is of course dependent upon the result of a comprehensive evaluation to confirm your candidacy. The great news is that with custom wavefront or topography driven laser procedures fully 99% of patients who are good candidates are enthusiastically pleased with their outcomes and many can see better than they did with glasses or contact lenses.