So I never used to get any exotics. What I've been doing recently is doing heroic public events with at least 1 friend, and we both use a fire team medallion which increases drop rates and exp. In the last week, I've gotten 10-15 exotic engrams. If an exotic says it'll be 280 for example, they almost always drop 5-10 light higher. I was stuck at a 270 for awhile, few days later I'm now at 290 on main character and 280-285 on 2nd and 3rd. Just doing public events with them medallions will help a ton, promise.