Currently pregnant with DC2, nausea first time around was horrendous and I was like you I completely lost my appetite and barely ate. I lost about 10kg by 12 weeks and was depressed.
This time around I’m determined to do everything I can to help myself get through it. Personally:
I’ve already been to the doctors and got anti sickness meds, I’m only 6+5 I waited until 16 weeks last time, that was too long to suffer.
I am loading up on carbs even when I don’t feel like it. Have you got a supportive partner who can virtually force feed you toast? Joking...but I’m getting OH to just bring me toast with butter a few times a day even if I don’t want it. I end up eating it and feeling slightly better!
Fizzy water is helping settle my stomach better then flat drinks. Although I HATE drinking any fluid at the moment.
Travel bands intermittently throughout the day.
Get up, shower, clean your teeth. I find that takes the edge off even for 15 minutes.
Lastly - don’t stress about baby not getting nutrients. Your body has loads stored up from pre-pregnancy and right now it’s your hormones doing all the work as the placenta hasn’t taken over. Baby is taking everything it can and is completely fine...it’s just you that feels shite!
Sorry for the long message - you have my sympathy! None of this will make it go away but it takes the edge of rather than it being debilitating and taking over your life 
I bring you this message lying in bed feeling like I’m about to throw up...time to force feed myself toast...