Vomiting and acid indigestion are very common with the gastric sleeve. I had vomiting up into the forth month after surgery, acid indigestion is an every day thing. Hard proteins were the worst, stick to soft protein wedge cheese and cottage are a good ones, for me cheese in general works well. I stay away from chicken and beef unless it is ground and cooked in chilli or a sauce. soft is the way to go. Along with eating only one or two mouthfuls at a time, taking your time and chewing will also help. Grease is out of the question; I tried a falafel, one time and repaved highway 101 with green slime for ten miles. The good news is that the nausea it will subside in time, weeks or months and no matter what you may think you won't starve. One last word, don't drink anything before during or after eating. Been there, done that, got puke on my T-shirt.
Keep in touch and let us know how you are progressing.