At some point of a beginner cycle, you are not going to be able to progress on a full body routine. You need to split it up.
Day 1: Squats
Day 2: Bench
Day 3: Deadlifts
You can put a day of rest in between if you want so you still have 3 training days. You can add on 2 or 3 accessories after main lift, hitting the same muscle group, such as rows after deads or tricep work after bench.
Take the weekend off. Rinse and repeat.
Protein: your random bodybuilder is a retard, unless he thinks that all protein meals are a protein shake. For example, if you eat a big T-bone, you are eating more than 50g of protein. But it takes hours to digest so you aren't "pissing out" the extra, your body is able to get a steady stream of amino acids over 5-8 hours.
Just eat real food and make sure you have some healthy fat as well with each meal. Your body needs it for recovery plus it slows digestion and cuts down on nasty insulin spikes.
At 50+ years old, you have a huge potential to improve if you take recovery seriously.