Enmity problems as a PLD.

[isomy]

During AoE pulls I usually flash at least 3 times and circle of scorn the mobs before I begin using my combo if that helps. If DPS is pewpewing only single target while you are doing a large pull they will pull some mobs off of you. Part of DPS job is watching the threat level they generate as well.

[Enclavex]

Your Ilvl is more than decent, you should not have any problem holding hate unless your dps start the fight before you even shield lob.

You mean Bards barding it up.

[DxWings]

Hmm...in that ilvl range you really shouldn't be losing too much in terms of aggro.
To start off a boss pull, this is what I do:
FoF -> Shield Lob -> Spirits (weaved) -> Rage of Halone -> CoS (weaved) -> Fast Blade -> Savage Blade -> Rage of Halone
That raw RoH after Spirits Within allows you to get a head start on enmity as your DPS is starting out their rotation (the start of most DPS, if not all, rotation is low in potency, so aggro is generated slowly on the start of their rotation).
And this is without being specced in STR gears/bonus points.
And yes, like others have stated, Flash has very little use in enmity generation on single target. You'll be better off with the RoH combo.
The only times you'll come close to losing enmity or even lose it for a sec is when a current-geared BRD has all of their cooldowns up and they pop them all without Quelling Strikes. They'll easily overtake you in aggro, if that is the case. However, since its a boss fight don't panic and try to voke immediately but throw Cover on the person who pulled ahead in hate (in this scenario, would be the BRD), and take that time to build up a combo'd RoH. Once you have that combo'd RoH, voke the target and immediately use that combo'd RoH.

[Synestra]

Don't fight or flight before shield lob. Lob -> FoF -> Scorn -> combo

This is the opener i use aswell due said double scron under FoF buff, there is like 2secs or so left in FoF when scorn comes from cooldown.

[Synestr]

Flash isn't that bad to use on single target. If the blind sticks it helps with dmg mitigation and gives you time to Stoneskin or whatever.

I agree that FoF should not be used on your lob, it will waste active time. I use the following and have only rare occasions where I lose threat.

Lob > Flash (as I run through the mob) > FB > FoF > SB > CoS > RoH > FB > SW > SB > RoH > Bash (SWIPE if it's up) > Flash, this allows you to get the most benefit from your 20s of FoF. From here you can just 123 using CoS and SW when they are up, flash when you want, SS etc.

I think what may be happening in your rotation that you posted is that you front load a couple of moves that aren't boosting your enmity -

...I usually start out a boss pull with something like Fight or Flight -> Shield Lob -> Circle of Scorn -> Fast Blade -> Flash...

Most DPS are trying to smash that boss from the get go, with a ramp up of 2 or 3 OGCD (BFB, IR, RS), with this being the case they are generating threat in their opening that you are with yours. By the time you get to your flash, you are just starting to catch up. Make a slight adjustment and you should be ahead in threat.

This is the opener i use aswell due said double scron under FoF buff, there is like 2secs or so left in FoF when scorn comes from cooldown.

Though I agree that it's nice to get in two CoS under FoF, but for ST as the OP is concerned with, I don't see the benefit. Sure the DoT is cool but you would be better served to ensure you get more of your threat combo in during the up time of FoF. NOW for larger pulls, yes, FoF before CoS is a good idea. Better AoE generation and a little DPS are always welcome.

Hope my advice helps!