Been having brown discharge for a week now, have unprotected sex,been on depo for about 9 mnths is the excessive discharge due to hormonal imbalance ?

Hard to tell you: The cause of your "excessive discharge" may not be determined without a Gyn evaluation, examination of your vagina, cervix and some microscopic and microbiological tests of the discharge. Remember that "unprotected sex" increases your risks of STIs ; long-acting-reversible contraceptives like intrauterine devices and subdermal implants are much more effective (>99%) than Depo-Provera (90 to 94%)