I'm in a similar boat to you - met my partner at 19 and it was my first relationship while they had more experience. We've just celebrated the 5 year mark.

Do I sometimes get those feelings of having missed out? Yeah, of course I do, especially when my friends are sharing their stories. But when I step back, and actually look at the situation, would those experiences be better than what I have now? I can't change the fact that we met when we did, only what happens going forward. The desire to try the dating scene just doesn't measure up to my desire to have someone who gets me, and I who I know will always have my back. Not even close.

But that's just me, and for you it might be different. Take some time out to examine your feelings and try to figure out where they really come from - whether they are just wistful 'what-ifs' or something stronger - and proceed from there. There might be ways you can fulfil those desires within the context or your relationship (roleplaying, sexual experimentation, etc), but you need to know what your feelings actually are before you can find a solution.