I guess i would suggest to try laying off the weed for your next trip and see how you go, as weed does intensify the trip and body load. I am also a person who gets pretty paranoid and anxious if i feel sick enough to need to vomit... as i struggle with
emetophobia which is a condition where you fear vomiting. Do you fear vomiting even if you are not on drugs and come down feeling sick? Say if you get gastro, or even drink a bit too much..?
I have never vomited on psychedelics, but i have definitely felt pretty damn ill during the body load in my time. I just keep myself busy through that time, make sure there is good music around me and drink plenty of water through that period. Lay off any alcohol or weed through out the body load phase i would say.... i personally start smoking weed when the acid is starting to ease off a little, as it kicks it back on and i get more out of it

Or ill just take more. Ha!
You'll be fine mate. I have seen friends vomit on acid and not once did it get out of control. If anything, i envied how stronger their trip seemed to be! I am sure if my mind would let me, i would have puked many times... but because of my stupid condition with vomiting, a lot of times when i need to vomit, I cant and end up feeling worse off.
I am just grateful i tend to handle psychedelics really well when it comes to nausea, i feel a lot more in control as compared to if i am on pills etc.
I will say though, mushrooms do tend to trigger nausea even more so than LSD does, so be weary. Start off on a very low dose and slowly take more. Pace it out....