One of the best things about training younger kids is that I'm reminded of what training used to be like AND what training is like for many people. It's easy to get lost in all of the years of training and either forget or romanticize the past. So while getting stronger was always my priority, even when I was very young, I could have done a better job of building muscle. And by building the muscle, I could have gotten much stronger.
Now before everyone goes Ronnie Coleman, "building muscle" doesn't mean you turn into a bodybuilder. it means that you employ some body building methods to your training and do so appropriately. And it also means that you eat so that you have the calories to build the muscle. For the sake of a strength program, the assistance work is done "bodybuilding" style. Meaning higher reps and working the muscle (not the movement).
Building muscle became a priority for me, as a coach, after listening/reading to Boyd Epley talk. For power athletes, especially young ones, building muscle will result in building strength. And with many young lifters (or new lifters...not necessarily young), building muscle will be the difference in how strong you become. ESPECIALLY with the press and the bench press. These lifts, for a variety of reasons, progress slower than the squat and deadlift. And one of the reasons is because the lifter has very little upper body mass.
As always, there is a balance between strength and building size. But if you aren't eating/training to build muscle - and your bench/press is in the dumper and has been for awhile - maybe it's time to build some muscle on the body and see if that gets you over the hump.
Choose a program that makes sense for your schedule and increases your volume. If you don't know what you're doing, don't modify it or try to blend different programs together. The volume increase can be with bodyweight movements or weights depending on your current ability but either way, be prepared to adjust your recovery for some increased soreness. Make the plan and stick to it for at least 3 months. And keep your own training log! Grab an inexpensive notebook, make it your own and keep notes. And finally - EAT.
If you want a detailed option read Building The Monolith: 5/3/1 for Size