What drug can I replace heroin with?

I'm going on subs but I find living life almost intolerable sober. I was thinking maybe mdma every so often? But I feel like nothing compares to heroin.... im thinking maybe I'll just do a last hoorah and do heroin for two weeks. But I hate the adjusting period to subs. It takes 4 days for me to feel normal. I've been sober for a little under two weeks now.