Many players are complaining that there aren't enough quests to effectively solo to 81-90 with SF
content alone. The entire NE section of the Toxxulia Forest Station area is devoid of any quests, which looks like it would have been a bunch of  -  ones had they been present. Currently you sublime directly from finishing with the  - some  Hua-Mein pandas then onto [86+] Stonebrunt Highlands. So you may suddenly seem to start doing quests +1/+2 levels beyond your own.
You either need to also: do crafting timelines, grind mobs, or mentor down and go do some 80 content (old content you never did, or some new ocntent they added with SF to round out the Golden Path).
This has been particularly noticed around 87-88 since Stonebrunt Highlands quests are usually drained by then, depending on what quests you did when as well as whether you have been augmenting XP with The Hole or other instances, or not.
I have done almost exclusively combat quests (I don't craft atm), and I am in Highlands doing  -  quests already, but I am 1/3 into level 85.
So be prepared, or try to augment as you go along to avoid getting stuck with no quests late.