It's a great revelation to realize that your stutter is not as bad when you speak slowly. So, firstly, celebrate that! I think it can be utilized best when you start stuttering badly. Once you notice your stutter acting up, try speaking slower. This way you can use the slow speaking only when you need it, to your advantage, and you won't have to worry about sounding too slow all the time. A little of both might work the best, but it's on you to discover what works best through trial and error. I hope it works out well for you! Keep us updated.