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if you love her, don't worry about what other people say.
what you did wrong was your drafting and concepting skills are trash, like people are saying. even for a cartoon there are a lot of things that could be done better. the terrible rib cage is one of them, don't try to fake anatomy you don't know. and she needs to have balance. don't feel pressured to change her design because of what people say, those spikes are fine for feet, maybe they are super hard spikes that can support her weight, these guys /ic critics don't have a good imagination. but at least have an even weight distribution on them.
that having been said, because you like it, hold on to it, put it on your wall, do some shit like that. then practice drawing for about 3000 hours. then try to revise the character and give it a new illustration. that will make you happier with her and (if this is what matters to you) other people will have more to say than just euphemistic complements.