Can you grow a little more although a carpograma presents the epiphyseal lines of the metacarpals and phalanges closed?

Depends: If the epiphyses of the long bones have not closed there is still some potential.

Not much more: Growth plates throughout the body close at different times or ages. At 18 most of your growth plates are closed and the ones that are still open are not likely to add much, if anything, to your height. Some people are "late bloomers" and grow untill 20 or 21, but this is not common. Either way, not much you can do about it.