@Nathalie-Kranich hmm... this is a very complex question. If you have a lot of work but most of them are not there yet or not relevant to your target market, then I’d say keep it small but if most of your work is good, I don’t see the harm of posting more. If you have vignettes telling a story and in good quality, add them but I’d discourage including character/prop designs in your children’s book portfolio. Perhaps place them in a separate tab.
Currently, your portfolio is lacking in kid diversity and sequential illustrations. So I’d really recommend working on those. There’s really no harm even if you add 20 new pieces as long as they adress the things your lacking.