Yes, you have beautiful children! They all have such striking looks!
Personally, I won't do the whole child model thing. There is not much money in it and I would hate for my child to ever feel 'rejected' on his/her looks. I recently saw a documentry on a mother who's toddler models for adverts and magazines and TBH the mother came off looking like she was pushing her child into it and 'doing it for her own satisfaction'. She also spent a large amount of her time driving him to shoot locations (she was a SAMH), waiting around for long periods of time and then sometimes being turned away because her child was 'not right' on the day.
I am not saying for one minute you would be anything like her! I just saw this doco and thought there was no way I would do that to my child. Your children are beautiful as are your photographs. I bet you have many albums filled with photographs like that 
Good luck with whatever you decide.
xL