spoiled brat?

What is the general connotation of "amaenbou"? My dictionary gives it as spoiled brat, but since that's very negative I'm hoping it's not quite as negative in Japanese (since the word was applied to me, in what I thought was an affectionate manner XD). Is it a term and adult would call another?

As you've guessed correctly, the Japanese word is not that negative - it doesn't really come with the connotation of "brat" to begin with. It's more a term used affectionately or jokingly to refer to someone who likes to rely on someone else, can't go without that someone, as if that person is a small child.

Among adults, if said between a couple, it's simply a term of affection; if my boss ever said that to me (I hope that never happens!) that means he's telling me in a friendly manner to grow up lol.

It came up when I hugged the guy I like- he patted my head and said "Amaenbou da ne". So I'm glad it has an affectionate connotation ^_^