jumping confidence

[EventPony]

Ok, the Arab that I lease, Tiffany, is extremely lazy in the ring (she is an endurance and loves trails, so she is definitely not lazy on trails:D ). I'm afraid to jump her any higher than 2'3"-2'6", because of a few reasons
#1 she's very lazy, and im afraid shes not very safe to jump very high
#2 ive never jumped higher than 3' with her (not willingly, i was in a clinic and i had to)
#3 she nose dives over jumps and she practically pulls me off of her over jumps...so what will happen w/ bigger jumps??
Im sure she could jump pretty high (shes only 14.2, and 13 years old), but does anyone have any ideas how to build my confidence AND work her up to jumping higher than i jump now? (when no one is pushing me (like my instructor in a lesson), then i only jump, like 18"-2', but in lessons, i usually jump 2'3" to 2'6")
Im not sure how Tiffany is actually able to jump, but i know its a lot higher than what im jumping now.

[Showjumper]

Your confidence should improve when you see how well the pony can go and how she'll manage it. Try loose-reining (or lungeing) her over jumps. Watch how she moves, try and count her strides, see how she bascules (if she does) without a rider on board. If she's lazy and doesn't willingly go forward in the school, try popping her over some natural obstacles which out hacking - for example, instead of slowing down and going around that log in the path, go over it - much more fun and less likely to stress the pony. Make sure to give the reins when she jumps, and she shouldn't nose-dive. Good Luck!

[EventPony]

Ok..thanks showjumper....Ill try lunging her over some jumps (probably wont happen...lol, she doesnt lunge well) and see how she does...i'm pretty sure that me not releasing isnt the problem, but Ill try..Thank you!:D