Ideally you don't want to be failing on the last rep, you want to be failing on the 6th or 8th rep and then squeeze a couple of extras out with a training partner. Thats where the benefits come from.

As said your not really doing a weight training routine. More like fitness but without the reps. Speak to one of the instructors at the gym and get a plan made up. Stick to one or two body parts a night.

Your diet isn't great but I think some people take all this too seriously. We all have to lead normal lives at the end of the day and living on chicken isn't cheap or easy for some lifestyles. You need to get more shakes in you per day and up your calorie intake that way. If your sticking to Maximuscle I would suggest the progain or progain extreme as they are the high carb shakes designed specifically for the likes of you. The promax looks more focussed on protein. Have promax after your workout but try to sink a progain down you mid morning and one before bed.