Hi Sandman,
The main reason you are not gaining is that you are not eating enough calories.
Personally, I would use less machines and more free weight compound movements right now.
Include barbell bench press, barbell shoulder press, dips too.
Try and progress from pulldowns to chin ups, or use a chin/dip assisted machine if you have access to one.
And the most important - Heavy squats and deadlifts, also stiff leg deadlifts, you must do these.
It's good to see you are not just doing arms and abs like most beginners.
Do you do any arms at all though?
Get in the extra calories and enough rest and you will grow.
Don't think of yourself as a hardgainer.
What is it you are eating every 3 hours?
Good luck.