There are a few exercises you can do to get better at jumping on a looser rein and having confidence. This is just what I would do
1. Work on riding your horse with a loose rein. Start at a walk then work up to a trot. Say, for example, you get them in a nice easy collected trot and you loosen the reins. If he speeds up, half halt. If he slows, ask for more energy with your seat or legs. Once he learns not to break pace without being asked, jumping should go smoother.
2. For your confidence: Remember to stay calm. I know, easier said then done. But just breathe deep and remember a calm rider = a calm horse. Also, to gain security in two point, once you have worked on riding with a looser rein you can go up into two point as you trot around. Doing this will help build your muscles for jumping and build confidence in two point for both you and your horse.
Best of luck with those jumps!