You look a bit smaller here than in your "arm genetics" thread the other week. Weird.
Great work on the strength progress. +200 pounds on your squat in 7 months is, like, nice. Especially weighing 180-something at 6 feet.
That's one way about it. But, at the end of the day, size comes from food. Without eating enough (or really more than enough), there will be no muscle gains. Pretty sure that's been your issue for a while.
5/3/1 is a solid, reliable, and versatile program without a doubt, but there'd be nothing wrong with you doing a straight-up "bodybuilding split" or hypertrophy focused plan for 12 weeks or so.
Again though, it's worth repeating that if you don't eat plenty, you'll waste your time.