A coeliac blood test won’t work unless gluten is consumed regularly. Antibodies against gluten are only detectable when you’re eating it in your diet. Even if you had coeliac disease and took a blood test, you’d possibly get a negative result if you tested whilst on a gluten-free diet.
If you currently are on a gluten-free diet, you’ll need to switch back for around 6 weeks before taking any blood tests for accurate results and eat more than one gluten-containing meal each day (e.g. cereals, breads, or other grain products that include wheat, rye or barley)
If this option is not possible for you, it might be worth seeing a specialist to discuss other ways to diagnose coeliac disease.