It is more than likely your trainer.

I had a cheap Blackburn Mag trainer. I didnt know if I would even like it so I got one of the cheapest I could find. The resistance was lacking. I did my FTP test and was in the 52x12 and really needed more resistance.
After the Blackburn started making a god awful noise, I got a Bkool Smart GO(so kinda apples to oranges). The simulation does make for a more realistic ride, but it will never be the same as going outside to me. A trainer is always going to be all work and no play, but the simulator does give you something to focus on. Even if you get a better trainer that isn't a smart trainer, I recommend doing a programmed workout so you have something to focus on instead of just mindlessly spinning.

Edit:

So i just looked at your trainer and it was a bit more expensive than the one I was initially using. the fluid should get thicker the faster you spin the drum. It should be more realistic than my mag trainer was. What cadence are you spinning at on the trainer? do you typically Mash or spin?