It's NOT too low. You just need to make your own groups. Just make sure you pull your own weight and players will want to stay with you. Spam Trade/LFR with LFM Mythic+2 Boosting Group - Must be 845-850+ ilvl. Follow this with spam for people to boost through with their key, you will get a handful of players with 810-830'ish ilvl, maybe even some with 850+, aim for 2 chests, 3 is a bonus and you're good to go.
All you need to do is put some time/effort into creating a group and you're good to go. Here's some inspiration. I hit 110 on my Hunter less than a week ago, I'm already 855 ilvl with not a huge amount of luck, just consistency in creating Mythic+ groups and making sure I create all of my own groups for normal Mythics. I aimed for at least 1 other mail user in the group incase they get unwanted loot and all was good. Granted you NEED to pull your own weight otherwise people won't want to play with you, just make sure you understand your class and you can maximize your potential.
Either way, 845 is fine, just don't expect an invite to groups.
(
http://eu.battle.net/wow/en/characte...aurus/advanced - Evidence)