I think you are on the right track by trying to get your hips going. But it sounds like you just haven't given it enough of a chance yet. You may be lacking some of the functional strength required to do it well. Practice, practice and more practice will help you get comfortable with it and build up the necessary functional strength. For example, it takes core strength to push the hips out while keeping the torso close behind. And, assuming you don't sacrifice your knee lift, it takes strength to get the stride leg out front in a timely manner given that your hips are getting out sooner/faster. I'd expect that the more comfortable you get with it, the better your timing will get. But if you still need adjustments to get your timing right, try to make the adjustment with your lower body.
Tom House and the NPA have some drills that would be worth doing:
(1) Cross-overs: This drill involves both flat-ground and mound work where you pitch from a starting position that has the stride leg/foot crossed over in front of the pivot leg/foot. This position makes it pretty much automatic that you will get the hips going. You'll feel like you're going to fall down but your stride leg will catch up and keep you from falling.
(2) Narrow Stance: This is similar to cross-overs but your legs are simply
touching together (back toe to front arch) instead of being crossed over. This drill puts you closer to your normal stance and should be done after
(3) Towel Drill: This drill lets you work on your mechanics and timing without the stress of throwing a ball so you can do lots of these. The goal of the drill is to have perfect mechanics and timing the result of which is getting the release point out front far enough to hit the target with the towel. Hitting the towel is merely feedback that your mechanics and timing are good - it is not the goal.