Hello I've Been Diagnosed With Coeliac Disease Three Years Ago

Hello I've been diagnosed with coeliac disease three years ago by biopsy, I have followed a strict gluten free diet, initially my body felt good but for the past 5 months I feel excessively bloated, uncomfortable and gassy. Is it possible gluten-free bread caused this and if not what could it be? I also take levothyroxine and have remained underweight for many years despite eating healthily.