First, a comment on what Hunnybunz said about your yeast and its capability... The yeast stops when it runs out of sugar or hits its tolerance, whichever happens first, and with yours at 1.000, it's essentially out of sugar, I would be surprised if it went below 0.990. Even if the yeast is rated to 16%, it can't make more alcohol than it had sugar to convert, and with a must starting at 1.090 you're not going to get much more than 12-13% no matter what your yeast is rated for.
When you ferment something, one of the byproducts is carbon dioxide, which stays in solution for a while. Thinks like stirring and racking can dislodge it and that's probably responsible for a lot of the bubbles you got when racking but if you're really concerned, siphoning works a lot better when the container you're emptying is above the one you're filling. Then all you have to do is get it started and it'll keep going itself unless it equalizes the liquid level.
Your lees layer could be from stirring things up OR sometime when a mead looks clear and you agitate it (ie, racking) all the tiny little particles you can't see are attracted to each other and become big enough to fall more quickly out of suspension, I've had that happen after bottling, it sat clear looking for months, then I bottled it and all this stuff settled out... should have racked it once before bottling and let it sit for a few more weeks! Truly clear means if you shine a flashlight through the glass you can't see the beam in the liquid, until that point you're still going to end up with stuff settling out.
If it doesn't smell and taste like vinegar, that sharp distinct acetic acid flavour and aroma, it's fine. And I've been intentionally trying to get one wine to turn to vinegar, for me anyway it seems to take a LOT of oxygen to get it to go.
Also if you want to know if sweetening it will fix it, draw out an ounce or two and put a little sugar in it and see if that makes it a little less bitter. Tea and oak both have tannins that can really give a mead some pucker-power (you know like that astringency you get from some red wines?) but that will mellow with age and so will the harshness of the alcohol, I've got one batch made with barely ripe highbush cranberries that's so tannic and bitter that it's been aging out for several years now and is finally approaching drinkable, probably another 5 years before it's enjoyable so I live and learn, half as many cranberries in the recipe and make sure they're ripe next time.
I also this year managed to make an overly-acidic red currant wine, a few teaspoons of calcium carbonate really helped, if it is too sour from acidity it can really enhance any bitterness that might be there.
Short answer - your mead is probably fine, just give it time and maybe some backsweetening. Most meads and wines (especially dry ones) taste pretty awful at 2 months unless it's Joe's Ancient Orange!
"The main ingredient needed is 'time' followed closely by 'patience'." - The Bishop 2013
"Good grief! If someone wanted to murder you, all they would have to do is ship you a 55 gallon barrel of honey and watch you document working yourself to death!" - Vance G