Why am I always constipated? I’ve tried everything. I want to poop everyday.

Went to three gastroenterologists. I bloat a lot and it is noticeably due to constipation as shown in lab imaging. I know I’m backed up. I poop every 4 days. It honestly makes me feel depressed the longer I go without pooping. I just want to poor everyday and tone down my bloating. I was never diagnosed with anything. I have tried everything for the past 5 years: Linzess, more fiber, belly massage, more fruits and veggies, more water, fodmap, dairy free, gluten free, sugar free, prune juice, psyllium husk, herbal supplements, all laxatives, tea, exercise. I’m actually so healthy and fit. I don’t use straws or sleep with mouth open. I don’t eat processed foods a lot. I really don’t understand why I’m like this.