Agreed with Paul as well as with what you said - DOMS is not necessarily an indicator of success. I am not trying to be critical of your training regimen, but I don't seem a lot of reasoning behind it? I also think your supersets are possibly counter productive. I usually use supersets to pre-exhaust a particular muscle. For instance, I will do flyes and then incline bench presses - so that my chest gets the full benefit of the bench press.
You finished with the 20s, what weight did you start with on the curls? How many pullups can you do?
If it were me, and everyone is different, I would re-arrange what you do slightly and get rid of some of the movements. You don't have to do them all just because you can.
I like to start big and work down. For instance, I train chest, shoulders and triceps (in that order) on one day. As I train chest, my shoulders and triceps are getting stimulation, as I train shoulders (depending on what exercise I'm doing) the triceps continue to be stimulated, and then I train triceps last. If I train triceps first I will lift the heaviest weights in those exercises, but my chest and shoulders will suffer because my triceps will now be weaker and will thus become a big limiting factor in how much weight I can push.
If this were me, I would train around the big three - Deadlifts, Squats and Bench Presses. On back day start with deadlifts, then go to rowing, then pull-ups, do your under-handed pull ups right before your biceps routine.
I would then do 1-2 curling motions for the biceps.
On the curls, throw on as heavy a weight as you can handle for 6-8 reps. Go to failure and keep the volume low.
I can bang out a back/biceps workout in 30 minutes and I will be sore for days after. You may just not get DOMS very much....lucky. But I know what you mean about getting validation. It hurts so good
Cut out all the post workout curls and **** like that. You are either stimulating growth or recovering.
Cut out your lunch and post workout workouts. It is safe to say you have not recovered or grown since your morning workout when you get home at night - stimulating again will NOT create extra protein synthesis and will only burn up calories and such. You are wasting time/effort here I think.
If you really want to workout 2X/day then I would do all of your back in the morning and then just your biceps in the afternoon. In other words, training the same body part twice in one day is kind of pointless. Train it all at once and let it rest.
Or you could re-arrange so that you did Back in the morning, chest and triceps in the afternoon and then Legs in the morning of day be and shoulders/biceps in the afternoon. This would get you in twice/week for each bodypart if you worked out 4 days/week.