You don't need to see a GI specialist except if you want that endoscopy (I skipped that, and the Gastro, too). Your GP should be able to order the follow up tests for you.
Request the bone density scan. It's a good thing to check.
Request nutrient levels are checked. Ask for: D, A, B12, Ca, K, Mg, Zn, Cu, folate, ferritin.
Daibetes (T1) and thyroiditis are the most common associated conditions with celiac disease. Your cancer risk was just slightly elevated while living undiagnosed. Once you are healing, and your inflammation levels fall, your risk of cancer will fall back to normal range. It really is one of the less common complications of celiac disease.
Genetically, you are at a higher risk of developing other autoimmune diseases, but staying gluten-free will lower that risk as well. Just be aware of future symptoms if they pop up, and have them looked into. Try not to worry too much. Most of us celiacs who have multiple autoimmune diseases developed them while we were living undiagnosed. Living gluten-free will help you in the long run.