So your comic looks really cool as is, but I feel like color certainly wouldn't hurt it! Especially if you're already doing shading--it honestly wouldn't take much more to just be a full colored comic. Just number wise, colored comics tend to sell better than black and white.
If you want to keep doing the shading, you could always pay someone to only do the flats. It takes out the tedious parts of coloring, costs less, and you really wouldn't be adding any more work on your end. That doesn't mean you HAVE to retroactively color all of your pages though, you could always just start having it in color from the next chapter onwards or something. Maybe get the old ones colored only if you can afford it.
I totally understand how it might make you feel a little weird to have someone else work on your stuff. It's kind of odd at first and having been in control 100% for so long is hard to let go.
But, as someone who works with a small team (5 people, including me), it's completely worth it! The great thing about working with other people is that sometimes they're stronger at a skill than you are and it enriches the product in a way you couldn't. Pick someone who is equal or better than you in choosing colors, and, if you decide to have them do all of it--better than you at shading. As long as both parties respect each other, it tends to turn out awesome. I wouldn't be where I am today without my team.