I just found i have a growth hormone deficiency but is it too late to grow?

Likely: At a listed age of 40, you could have simply had growth hormone levels drop off with age, as they do in everyone, but more than expected. If they were normal during the teen years, which we cannot know, you likely cannot blame this for your height. If the growth centers in your bones are closed, as they do in most by late teens, you cannot grow taller.

Misnomer: "Growth hormone" is a poorly-named hormone that continues to function in adults, though we don't know exactly how. A spot growth hormone assay is worthless but if you have low IGF-1 and/or some other appropriate assay, you might be one of those (rare) folks who will feel incredibly better on replacement of the hormone. This is controversial. I'd get two opinions.