Digestive issues when Introducing meat

I feel quite alone with this problem. I have read other post with similar problems but no one seems to have the same sensitivity like I have. I tried a vegetarian diet for a year but got issues with iron and other things so I am now trying to eat meat again. I get bloating, gas and constipation from just 100g chicken, I have read that I should slowly introduce meat and go from the easier one to the more harder ones but it seems to me that I have to go so slowly and carefully with this, that it doesn’t seem normal. I hear other people have been vegan for like 10 years and have it much easier. Are there others out there that are similar to me? Will it get better? Any tips?