Welcome to our forum.
Polyamory unfortunately kind of has "polygamy" attached to it at the hip, and polygamy does indeed have a bad reputation. It has long struck me as odd that polygamy (which should be called "polygyny") allows multiple wives but not multiple husbands. This thought is what kind of got me started on my own journey to discovering and accepting polyamory.
I think you will find this a good site with a positive take on polyamory, and many good links and resources. Take full advantage of it, read the various threads that call to you, and post any thoughts or questions that you have.
It sounds like you and your husband have a great relationship with each other, and are very accepting of each other. That's a great thing to hear, and it will be of a lot of help to you on the road ahead.
Pleased to meet you and have you here,
Love means never having to say, "Put down that meat cleaver!"