The nutritionist recommended them, BECAUSE SHE KNOWS IF YOU BUY IT, SHE GETS CREDIT AND IT MAKES MONEY FOR THE STORE. You know what the recipe for gaining weight is? EAT. EAT A LOT. And don't tell me you have been eating a lot. Eat constantly. Eat until you feel sick to your stomach, then take a dump and eat more. Eat til you feel like puking. Eat lots of meat. Buy big jars of peanuts at Wal-Mart and eat those at all hours of the day. Eat lots of PB+J or PB+H sandwiches. After your workout, drink a quart of milk, then go home and drink more milk throughout the day. Eat everything (but try to keep it as clean with healthy food as possible) Gain weight like a MAN.
And as for how you should workout to gain weight? Squat. Squat like your life depends on it, then squat some more. Deadlifts are great to add too, and if you know how to do them, do power cleans from the hang and do either military presses, push presses, or jerks. No machines or crappy isolation maneuvers. Oh yeah, weighted chins and dips, and bench presses are also great for mass. No training to failure, if you train hard enough using these compound lifts it will be all you can do to train 3 days a week. Even if you only get in 2 a week because you wear yourself out, then that's also all good. When I was bulking, it was all I could do to workout hard 2 times a week, and I gained 14 pounds in 35 days, almost none of that fat (granted I'm not as ectomorphic as you are, but due to that I didn't need to eat crazily either. You can do this too if you eat like a madman)
There, now you know how to bulk, bulk clean, and bulk WELL. There's really no way you can't bulk this way. No N-large. Pure protein powder is OK, but no weight gainer ripoffs.