I used whitelabs WLP400 yeast and the fermenter is currently about 68 degrees Faherenheit
I just read it takes a bit of time to fully attenuate, but it should go lower than 1030 if there are fermentables.
I had to google densimeter, never heard of it before. I don't have the gear to measure that just temp and gravity.
What do you use to measure your OG? I use a simple densimeter like the one on the left:
Still getting a handle on BIAB, its possible there are no more fermentables left. This was my second batch and the mash temp ended up being a bit high for the first 10 minutes or so until i got it under control.
It depends on how much "a bit high" means, but that could be. 154 is not a low mash temp and if you reached 158 or 160 that would denature a lot of enzimes. That's the kind of temperature that is needed to make very low alcohol beers, in the OG range of 1035-1038, so they don't thin out too much.
If you than lowered back your mash temp, you could have slowed down the remaining enzimes. Did you make a starch convertion test with iodine?
Anyway, I think you have to two choices here:
1) take a density measure now and one next week. if they are the same, bottle your beer, otherwise the yeast is not done. In this case, you can give it some extra time, you can go a bit higher with the fermentation temp and rouse the yeast again.
2) use a different yeast, one with a much bigger attenuation rate. I suggest Danstar Belle Saison. I use it for this recipe and it's an extreme attenuator, usually between 95% and 100%. That could dry up your beer.
If you don't know what to do, take a sample of your beer and taste it. If it's ok or slighly sweet, I suggest option 1.
I didn't keep track of temps the whole way through but 154 was the goal, and I mashed out at 168.
You should, it helps a lot to improve your brewing technique, both for debugging and for recipe repeatability.
In the future, for a yeast that you don't know well, I suggest a forced fermentation test too, it's very useful.
Cheers from Italy!

Piteko