2nd Trimester Nausea

I am currently 15 weeks pregnant and is still having extreme nausea. Nausea began about 5-6 weeks and has lasted ever since. It has not let up at all. I thought maybe around the 12-13 week it was subsiding as I have figured out how small of meals and how frequently I should eat them. I was wrong. Still having extreme nausea. I have tried medication they have recommended and even eating stuff I thought was supposed to be light on my stomach and nothing has helped. Any mamas out there have any advice on how to manage it? I’m desperate!