Been lifting for 3 years, no muscular strength improvement. What do I do?

I have been on and off weight lifting for 3 years now. I'll usually keep a pretty steady program, 3-4 times a week ( 3 full body or 4 split routine) for about 3 months, then get lazy, injured, etc. and take a month off. In the three years I have been weightlifting, I have not really improved my strength at all. I am 20 years old, weigh 165, and am 5'9". To give a specific example, 3 years ago my bench press max was around 215. Now, its 220. What am I doing wrong? Or have I reached my genetic ceiling? I do cardio workouts 3-4 times a week also, and eat ridiculous amounts. However, when I stop doing cardio and continue eating a lot, my strength greatly improves (haven't tried maxing but my submax reps increase a significant amount). The only downside of this no cardio-high-calorie strength improvement is that I start to get love handles so I haven't embraced this method of gaining strength. My muscle size is increasing but strength remains pretty much the same. I look WAY stronger than I am, which I guess isn't bad but Its kind of embarrassing when someone whose muscles are a lot smaller than mine comes up to me asking how much I bench and I end up benching less than him. I don't seem to have a problem gaining muscle and definition, but its like the extra muscle I have doesn't have any purpose other than decoration. I don't take any supplements except for whey protein post workout. What can I do to improve muscular strength that I am not already doing? Since my muscles have become more defined and maybe a little bigger over the years but I am still putting up the same weight, could this be a motor neuron recruitment issue? Another thing I have noticed is that my muscular endurance is extremely low. For example I'd finish three sets of military press (12,10,8 reps) and go straight to bench press and put up 135 lbs only 3 times when I could usually do 15 reps if that was the first lift I started with. I'd really appreciate any help I hate going to the gym and not getting any changes in strength!