Son gained approx 1lbs in a week?

I posted last week that my son's ped said that he was slightly underweight but nothing concerning as he is meeting all the milestones and developmental stages. He's doing very well and growing at a normal, healthy rate the only thing that was lacking slightly was his weight.

His ped suggested adding one extra meal a day of solids so that would up his meal intake of 3 times a day as opposed to 2. He also suggested adding more fats because he doesn't think he is getting enough which to be honest, he wasn't!

We starting beefing up his meals and adding in some more fats.

He has gained almost 1lbs in about a week.

His ped wants to see him again in a month for a quick check up on his weight.

He still nurses around 8-10 times a day and now gets 3 meals mixed with a variety of foods and good fats.

Is this too much of a gain? Worried we are stuffing our son with a ton of food!