There's no set amount of weight a leopard gecko should gain, that would be saying for us humans that there's a set amount of weight a 7 year old should gain when growing to 8 year old. As you can see, there are more than just the age variable. You have to account for genetics, as some geckos are meant to be bigger, some smaller. Like us humans, some are taller, some wider, some shorter.
Also some geckos grow faster, some slower. Some geckos will grow very slow the first 5-6 months, then explode in growth after.
Then you have to account for the environment, the feeding schedule, the supplements you use, etc.. I know you want to know whether your gecko is healthy and growing fine or not. The best way to tell is by observation. Look to see if the gecko is proportional, filled and not skinny looking. Look to see if the tail is plump, a plump tail is a good indication of a gecko that's being well fed. Observe to see if the gecko is alert, and of course after they eat, observe to see if they go within a day or two.
Also it's hard to say whether the amount of roaches or feeders you are giving to your gecko is enough or not. Someone could say they feed 3 roaches a day, but they could be smaller roaches. Where as 1 larger size appropriate roach would probably fill them up just fine. So it's hard to judge whether you are feeding enough without seeing the size of the feeders.
Generally for geckos around 7 month old, like yours, I feed mine every day. They get approx 2 super worms or 1 size appropriate dubia roach per feeding. They are all growing nicely with plump tails, so I know I'm not over or under feeding them. For adults over a year old, I feed them every other day, and about the same amount really. 2 super worms and 1 size appropriate dubia roach. When they get larger they can take down larger roaches, and I find 1 size appropriate dubia roach would fill them up just fine. I never saw them wanting second servings.
Good luck
