What can I do about my fragile teeth? I fear grinding will cause more to chip.

Night guard. Night guards fabricated and adjusted by your dentist to fit your mouth exactly area your best option. Soft night guards don't tend to protect your teeth as well.
Mouthguard, restore. See a dentist for a thorough exam to determine the cause of your fragile teeth. The dentist can treat this problem with crowns or other dental restorations. The dentist can also fabricate a mouth guard (aka occlusal splint, night guard) to protect your teeth from grinding or bruxism.