HELP!

I am currently 15 weeks and 2 days pregnant and have been having trouble keeping any food down for the past few days 😢 Does anyone have any tips or suggestions? I only weigh 38.1 kg ( i have struggled to put weight on my whole life ) and the midwife and doctor are telling me to keep eating even if I am throwing it back up. I am really concerned that bub isnt getting the nutrients he / she needs 😢 as I can't take pre natal vitamins due to them making me extremely sick!

Any help will be greatly appreciated!!!