Bottle Carbonation Worries....

I made a 6 % abv red ale a few months ago (my 8th batch). After 10 days in primary the beer tasted strange, so I gave it 20 total days in primary, still tasted odd. Thought I had an infection, gave it a month in secondary hoping the off flavors would go away, and they did. Oh, fermentation temps were 66-68 deg at all times.

When I racked and bottled I noticed the beer was abnormally clear, at 70 degrees. I racked, primed and bottled. It's been 12 days at 73-75 degrees and still no carbonation, I usually have some carbonation by now. Also, as far as I can tell there's NO sediment in the bottles at all. Normally after a week or so I can swirl a bottle and rouse something from the bottom, but not with these.

Is it possible that the long secondary time caused all (or almost all) the yeast to drop (or die) before bottling, and I don't have enough yeast to carbonate? It's just that it was abnormally clear at bottling time, and while it looked great, it usually isn't that clear at room temp.

I know the first answer will be "wait a few weeks, they'll carbonate", and I plan to, but what if they don't? What is a "reasonable" amount of time before considering adding more yeast? I've never had to add more yeast, would I put everything in a bottling bucket, add more yeast, and re-bottle? How much yeast? I've never used dry yeast, would "proofing" be necessary? It's just annoying because even though it's flat it tastes really good, and I don't want to mess up a good batch of beer trying to make it carbonate. Wish I had a keg... Oh well, any advice would help
Oh, if it matters, I used White Labs WLP001 yeast.

Higher gravity beers take longer to carbonate. I don't know the chemistry behind 'why' but it's just the way it is. I have a beer carbing right now that finished at 1.020 that is a 6.5% ABV beer, and after two weeks in the bottle, there are no signs of carbonation yet. I fully expect this beer to take 6+ weeks (probably closer to 8) to carbonate to a level where I'll like it. I don't have any lack of confidence that it will carb up. It was in primary for two weeks and in secondary for 3 weeks. This beer was also made with WLP001.

Hmm, yeah I plan on giving it at least a couple more weeks before I get really worried. I was just worried about the lack of sediment, which is probably due to the long secondary (thus my fear of not enough yeast). Normally, when I bottle it's pretty clear (5-6 % abv beers). If I swirl them after a couple days, nothing happens, but if I wait a week or more, swirling rouses sediment from the bottom. This still has no sediment.

I've never let a beer sit in secondary this long, so I don't know how long it takes for yeast to completely drop and what's "supposed" to happen. Maybe there's just less yeast, but still some? But "less" means fewer yeasties eating sugar which takes longer?