Sounds like technique to me since you mentioned the fly stopping the line like an anchor. You really need to have your fly positioned (this fly position is known as the "anchor) within one rod length or so of you when spey casting or else it really does act like a boat anchor that prevents the fly from being pulled up out of the water and cast.
The other thing is since you are new to spey casting, don't try to make long casts yet, they will come with practice. Right now you are better off working on technique (just like you did when learning how to cast with a single-hand rod, remember how you couldn't do that very well either at first). I'd recommend using 50'-55' of line and working on having very consistent anchor placement, "D" Loop formation, hand/arm position when making the final forward delivery (also known as the "key position"). Once these are good and consistent, then lenghten the cast by 10' and repeat until they are consistent, then add 10' to you cast, etc.
Doing it this way you will avoid developing bad habits and will be casting 80' or more in a relatively short time. You didn't learn how to make 65' casts with a single-hand rod in a few days, and you won't learn how to spey cast 80'+ in a few days either. Spey casting is different than overhead single-hand casting, so you need to learn a new set of casting skills, which doesn't happen overnight.