6 months in - is it too late to adopt a beginner barbell routine?

Hi, I've been going to the gym 5 days a week for 6 months now and have been disappointed by my increases in size and strength. Is it too late to start afresh with a beginner routine like those mentioned on the wiki?
My main concerns are:

• That I've wasted my potential for those beginner gains now and wont see much progress
• Dropping down to a 3 day routine isn't something I'm keen on, I would like to fill up those 2 spare days with additional exercises if possible
• The racks at my gym are very congested and switching to a barbell routine is going to require me to change my schedule and work out & shower before work

I acknowledge that I must start doing proper compound barbell exercises, is there a suitable full body workout for someone like me? Any advice would be much appreciated

More about myself: 20 Y/O, 6'4", 78kg

I've been doing an awful hybridized PPL routine that stemmed from me initially wanting to use ALL the machines because I felt intimidated by dumbbells & bars. I've been learning as I go though and now my routine focuses on some compound exercises and incorporates dumbbells. My weight has actually decreased over the 6 month period, but has been on the up for about just over a month, coinciding with the time I decided to start lifting heavier and dropped the small amount of cardio I was doing, graph here I'm consuming 2,800 cals, about 180g of protein and 5g creatine each day, and am sleeping for at least 7hr30. In the past couple of months I've been seeing slowwww progress in the exercises I prioritise (assisted pull ups, shoulder press machine, assisted dips, dumbbell chest press) and next to none in the isolation exercises I do. Here's a graph of the volume I'm lifting each workout it looks like progress but I keep undercutting myself by switching up my routine and lifting with varying form. That low point I circled in red is when I decided to increase weight and decrease reps after my progress stagnated. I saw quick progress but am stagnating again. I churn out on average 8 exercises per workout, going to failure on the compound ones, I've never felt sore in my muscles the next day.

I hope this paints a picture of how much fucking around I've been doing as I learn, I'm anxious but am looking forwards to focusing on a handful of compound barbell exercises. I try hard every workout but these diminishing returns have convinced me that I will always struggle to build muscle. I really hope switching to a proper routine is the solution to my issues and that I'll start seeing the increases in strength and size I hoped for when I started working out.

Please share any advice you may have and your experience, thank you :-)