welcome to MC!
How old are you? And being sore isnt always an indicator of not training hard enough for a workout here and there, but for the most part, you should be somewhat sore, and never being sore to me just means something isnt right, which i think you know and why your here.
So what is 5 x 5 plan? 5 days on 5 days off?
Do you train with free weights , or machines, etc...
We have loads of guys that can help, myself included. I am just looking for a little bit more info before laying it all out for you.