Hi Renny,
I'm hoping one of the medical doctors on this board will reply to this too.
True osteoporosis in someone as young as you is secondary to something else going on with you. Also in order for you to be diagnosed with osteoporosis, you have to have gone through menopause. A diagnosis is not given to premenopausal women.
If you haven't had an early menoopause, it may be that your bone density is low because you're still building bone mass and haven't reached your peak yet. We don't ordinarily test young people for this reason unless they have other health issues that will affect the bone.
As for treatment, there is no approved treatment for premenopausal women. Birth control pills could help if you aren't already on them.
You say you have GI problems. That can lead to difficulties in absorbing calcium which impedes your buildup of bone mass.
You need to get about 1200 mg of calcium into your body every day. If you can't do dairy, look for foods with calcium added. If you see a % sign, drop it and add a zero to get the calcium amount. 25% = 250 mg. You probably need a calcium supplement. It can be as simple as Tums. There is no good or bad calcium. Just get one that works for you. Take it with food twice a day. You body won't absorb more than 500 mg or so at a time.
You also need Vit D. If your doctor hasn't checked your levels, ask about it. The current recommendation is now at 1000 IU a day. I've heard that it may soon be raised to 2000 a day.
Go the the NOF website for a lot of good reliable information.
www.nof.org I hope this helps and that you get some answers from your endo.