I want to explore my sexuality, but I'm in a committed relationship

The most important thing I can say to you is that you need to be you. Not the 'you' that provides a turn on for your current partner but the 'you' who feels at peace with however you define your sexuality.

Sexual identity whilst crystal clear in some respects is a very complex issue in others. Many, many people will say how confused they feel and how fearful of making a mistake even if they’re in a relationship they value, as you are now. The fear of leaving someone and then looking back and regretting it is very powerful but if at all possible should be avoided at all costs. This is because it can prevent people from finding out who they really are, what they most need and often ends up with something that yes, feels good in many respects but at that core, fundamental level, feels like something is missing. 

Trusting who you are and being with a partner in whom you also trust are often key essentials to wellbeing and peace. Of course things get difficult for everyone sometimes. Those curved balls that come flying out of nowhere can leave any of us feeling sad, desperate or depressed. But feeling you know who you are at the most basic level is an essential ingredient in coping with everything that gets thrown at us.

My very definite advice to you is that you get some counselling from a practitioner qualified in working with individuals who want to explore how they identify sexually. This is a journey that so many people embark on and provides that space and time to be with someone who has no agenda other than that they follow yours. You may find yourself amazed at how liberating that can be. 

As far as your current relationship goes, I think the problem is that you're constantly trying to decide if you should move on right now due to the feelings you describe. Well, that is certainly one option.

Another though is to enjoy what you currently have whilst taking time out to work with someone who can support your deliberations in the most helpful way. Whilst counselling is essentially a private activity, being honest with you partner about the possibility of exploring you feelings in more depth may be helpful and will hopefully help him to see that this conversation is about the importance of 'you', rather than something for him to get off on.

From what you say, it sounds like this relationship is trusting and caring one which you value. That's worth a lot but not to the exclusion of the most fundamental understanding of who you and what you most need in life. So, it's a 'both/and' situation. Enjoy what you have but be honest about your need for exploration and get some professional support to help you reach the understandings that are most important to who you 'are'.