Just because somebody told you that was the line to buy for that rod doesn't make it the best and only line to use.
Alot of times when I am out guiding , I am standing watching my client cast and thinking that new line they just bought is not the right line for them.
Then its my job to some how nicely tell them that line sucks and then set them up with a better line. It doesn't mean they are instantly throwing 90ft cast just because I gave them the line I like on that rod. When you have the proper line on it, the rod should be easy to cast with little to no effort. Anybody that has done enough steelhead fishing knows it can be long day of casting before you even get a grab.
There is some great resources online that will give you great info on what rod you might have and what lines and grain weights that work best.
Its still a good idea to go to a fly shop and see if they will let you demo some lines on the water.
For new spey casters it can be difficult to know if the line they have is right, until they have a better understanding how a spey cast works.
Here are some sites to check out if you think the line you have is not the right line.
Pay close attention to the grain weight of the line and the length of the head.