Great to hear you're in the gym and looking to improve yourself.
Even better to see that you have made some progress!
However in response to your actual question - you can do/expect a lot better
between mid December 2009 and early Jan 2010 (the last time I weighed in) I gained 6kg in 3 weeks, some fat but mostly muscle. I am 184cm tall and went from 76kg to 82kg, (I'm now probably a little more than that).
I am not genetically gifted when it comes to weight gain (I finished puberty and 56kg) and it has taken me almost 6 years to put on the 30 extra kg I now carry so I believe my results are typical of what a skinny man can achieve (with seriously dedicated eating)
without a doubt the most valuable tools I found in gaining weight (and getting stronger as the two are intimately connected) were heavy compound lifts and drinking 3L of milk a day (in addition to eating a normal meat and veggie rich diet).
Read the links Austy provided and have a think about where you want to go with your training and lifestyle (there is nothing wrong with a vegetarian approach but it's going to be very hard to put on weight eating like that - I'd even dare say this has contributed to your minimal gains in the last 6 weeks)
as I said to start well done on taking control of yourself and on your progress so far (any progress is good progress no matter how small) keep it up!