I am 26yrs old, bmi of 60 (from uk) have severe allergic asthma, due to have a gastric sleeve done. is this best for me? they say a bypass is to risky

Maybe...: Again without examining you directly; commenting on your case is difficult. Please get with your physicians and plot out the appropriate course for your weight reduction!

Diet & exercise: The best option is diet & exercise for weight loss. If you have given it a serious try and failed, surgery is an option. You have to be aware of the risks of the surgery; your surgeon can expand on that. If you can reduce your weight without surgery, that would be your best option.