Hi and welcome.
You say you are not satisfied with your marriage, but your husband is. That one comment speaks volumes about a certain amount of disconnect between you, and perhaps some unspoken issues that have needed to be addressed, but were not.
The usual advice is that it is generally considered less than ideal to seek out polyamory when one is not happy within a relationship. The only way poly can work well and be truly satisfying for people in an existing relationship is when they have a very strong, happy, and loving foundation upon which to build, rather than complaints or issues that aren't getting resolved. Having more partners won't fix what's wrong with your marriage, or what you are dissatisfied with. No one can ever really expect another person or relationship, whether poly or mono, to bring them the happiness, satisfaction, and/or fulfillment that they feel is missing. If one is not happy, satisfied, and fulfilled within themselves already, nothing will make it better - people and relationships can only be temporary Band-aids unless a person resolves their own issues first and can truly be happy with their life as it is in this moment, right now. It's an inside job, basically. Without looking at that beforehand, engaging in polyamory will only make life and your marriage worse.
That being said, it doesn't mean poly isn't a good choice for you. It just may mean that you and your hubs would benefit from some deep soul-searching, couples counseling, and recommitting to what you already have BEFORE branching out into other directions with additional people. If one person isn't happy in a relationship, it still affects the other, whether they are consciously aware of it or not. Therapy can be a vital step.
Also consider whomever else you might want to become involved with - no one wants the burden and responsibility of fixing another person's personal problems. Nor would anyone want to feel like a replacement for a partner that someone has complaints about. Not saying that that is your intent, but it is just that, very often, someone in a couple looks at other people as a way to get out of something painful or fix what's broken, without thinking of the impact of that approach, not only on their current partner but on the new person who is now supposed to be the answer to everything gone wrong.
For some couples, it could take a year or even longer from the time the topic of poly is broached to the day they are actually ready for it as a couple. Do not rush this! It could be disastrous if you do. But if you thoughtfully and methodically take your time and work to make the relationship you've already got to be the absolute best it can be, then embracing polyamory could simply be a wonderful aspect brought to your lives.