I've made quite a few brews of ayahuasca in the past. Tried different combinations of b. caapi, mimosa, syrian, peruvian t. etc The first time I made a brew, I got barely anything, a bit of visual and more space to sound. The second time I used a bit more material, kept it down for at least 30min with barely any change apart from the sense of syrian rue, then as soon as I allowed myself to throw it up, it was coming on smoothly fast (the fracticals in my sick looked rather nice) I wiped my mouth, then lay on my bed for some of the most forfulling hours of my life.
The third time also worked well. Now after the third time, got completely nothing. tried again -nothing.
What you need to be carefull doing, is doing what I did out of fustration -"fuck this, it's not working so I'll just use back-up plan b & c now" only to be pounded within a minute with so much unbearable nausea. I can handle a lot of things in life of all the variations, but that nausea I experienced was absolutely awfull, and took more mental effort than anything I've done in my life, and ever will (I hope). I actually found it hard to breath, breathing became no more automatic, I had to manually do it, but I'd keep forgeting to, becuase the nausea would almost make me completely unconscious. That day was also the most embarressing day for myself, as I had to phone an ambulance for myself, as I was alone and it was getting more intense. I'm not at all afraid of the inevitable -death, and I'm not really close with my family, but the thought of them, and anyone discovering me dead from ayahuasca made me call them. It took me a whole year to even have a spliff after that. And what's most fustrating is that I still didn't even get much of a trip. It would of been nice to be entertained at the same time, but got nothing apart from a few white mosaics which I would see anyway during meditations or just trying to allow them to visually occur at that time in my life. If I didn't have the nausea it wouldn't have been much of a trip. That whole experience I think was a blessing for me, I thought about alot of crutial things that I needed to think about at that point in my life during moments of that experience. It's been years since that event now and I've now matured greatly.
All you need to do, is just a bit more research on it. Carefully make the brew. Make sure your getting enough dmt and maoi's out in the brew's preperation. Then when it's in you, wait longer for it to absorb in you. Even try some different combinations.
Let us know how it goes