I don't know what the average is and it certainly depends on a lot of factors but I checked back on my health tracker and at exactly 3 months I had lost 51 lbs.
Great job! You will be there before you know it. I reached my goal of 140 about 6 weeks ago and have been trying to maintain. I am at 137.5 now and still slowly losing about 1/2 lb. per week.
My three month checkup is in two weeks and I expect to be at about 42-45 lbs. down too. Maybe for some of us, thats about right. But it probably differs person to person.