You are correct about "clingy". When I'm in a bad mood and my daughter needs me a lot, I might say "She is being so clingy!" "She is so needy" can also come across as negative.
"She needs me a lot", "he depends on me", "He relies on me", and "He is reliant on me" are not negative.
You could also say "My child never wants to leave my side" or "My child always wants to be with me, but I don't mind because I love him so much" Or to use some slang: "My child wants to be with me 24/7, but I don't mind because it makes me happy" :)