It's too late for a biopsy. You are already gluten free and unless you have zero gluten issues you will get very sick going back on gluten long enough for a biopsy. A biopsy is looking for intestinal damage, which means you have to intentionally cause destruction to your intestines with gluten to get a positive. You have to eat a lot of it for many weeks to do enough damage to show up on those shoddy tests.
Eat healthy, whole foods, but please eat plenty of carbs to give you energy.
Healing takes time. It took me 6 months to have one symptom free day. Give it more time.
People with autoimmune disease (I'm going to assume you have celiac and the test was a false negative), tend to get dehydrated. I needed to replace my electrolytes for several months, I drank good old Gatorade and it helped a ton. I tried other electrolyte supplements and all of them made me sick.
Hang in there. It will get better.