I had this with DS and it went undiagnosed.
Thankfully my new OB actually listened to me this time. They are taking me off Phenergan (thanks for nothing) and putting me on a Zofran cocktail (with stool softeners).
Please God, let this help. I honestly can't take this anymore.

Re: Officially diagnosed with Hyperemesis
I hope you get some relief!
What part of MD are you in? I'm in Westminster.
I'm in Pasadena, just north of Annapolis.
Hyperemesis is severe, unrelenting morning (noon and night) morning sickness. I am sick no less than 7-10 times a day. I hardly eat and I hardly drink. I've lost about 15 pounds.
I was dx last week too, I also went undiagnosed with my first pregnancy (7 years ago).
I'm blown away at how many people's OB will not prescribe them Zofran! Sure you can take Phenerghan, which will make you non functioning for hours on end.
FWIW, I keep taking my Zofran, praying that it'll help, but it hasn't. We're at 10 weeks and 2 hospital admissions. Boo!
I also had a diagnosis of severe hyperemesis with my first and now with my third. Keep your head up because I promise it gets better. The oral zofran wasnt enough for me so I am on IV's around the clock to stay hydrated as well as zofran through the IV.
ETA: Just saw your post about how much weight you have lost. That is not good! You are most likely dehydrated. I would talk to your doctor about taking more action. With my first I was also on IV's but still lost 11 pounds (I am a super small person) and they ended up putting me on a picc line. A picc line is a line that stays in your vein and has to be surgically inserted. Whereas the IV has to be changed every few days. They then began to not only give me fluids but a liquid food substance through the picc line. I had to stay in the hospital for 8 days. If anything ask about them putting you on IV's. It sucks a%# but its so worth it. Please keep me updated!