I guess I feel like I'm hitting a bit of a wall since I'm not able to do 5x5 of most exercises at max weight, adding 1.25k each workout.
There is not a single person this doesn't happen to, it's why Stronglifts has a deload procedure. But what you're not doing is trying all 5 sets at max weight. Whatever weight you're due to do, you attempt 5 sets at that weight. If you fail you get as many reps as you can each of the 5 sets, and you take the same weight next workout. Don't go down in weight for the last sets - you don't get stronger lifting a weight you can already do 5x5 for. And only after you fail a weight 3 workouts in a row do you deload 10-20% and work back up.
It's when you start to mess with these beginner progs that they usually stop working - different loading, incorrect deloading, different rep/set schemes, adding assistance exercises, tiring yourself out with assistance, not giving the main exercises the proper focus, doing too much outside of workouts, not enough (or worse - too many) days per week.
I looked at creatine the same way, looking for a way to push through a wall. It isn't a miracle cure, it makes a bit of a difference but not much. But the walls you're hitting will get broken down anyway if you're smart with your training, and also acknowledge that these are supposed to happen. You can't add weight every workout for ever, get that in your head early. Everyone stalls and it's part of the program.
If you feel like you're hitting a wall, drop the assistance (or do less - including kettlebell stuff) and see if that helps. Squats/Bench/Rows, Squats/OHP/Dead is plenty when you're trying to hit multiple sets of 5 maxes every workout. You sound like you're doing too much. After you deload 2 or 3 times properly on squats, drop it to 3x5 and when the same happens with that drop to 1x5 (drop the volume basically). If you're still stalling while gaining weight then, it's time to move onto an intermediate program.
Less is more.
(PS congrats on the weight gain)