Figured I'll throw my personal experiences in here and considering I'm a new I'll post where I actually know something...lol
I've been lifting and body building on an amateur level for a long time now even have competed in a few physique shows in Louisville over the years. I've not put a lot of thought into maxing out in years because I'm getting too old now (30s) and I've killed my shoulders over the years. However in my personal experiences whenever I've hit a plateau there's one thing that's always pulled me out - my diet. Yes, altering my workout helps (3x3, 5x5, 3x10, 4x20, drop sets, reverse tension, etc) but at the end of the day putting more in (calories, protein, good carbs) allows me to grow. Eggs, oatmeal, quinoa, sweet potatoes, tons of chicken, bison, and lots of almonds & macadamia nuts. I make my own shakes and if I HAVE to eat a protein bar I only eat quest bars. Working out on your own trying to max, be careful! I'd invest in a couple heavy kettle bells and start working some hinge exercises into your routine.
Do you reddit? R/fitness is a nice place to be a part of.
TL/DR: when in doubt, bulking, eat more.