Mandarin Club is pretty well respected in Chengdu as far as places to have a formal learning setting, in addition to universities. Search on the forum and you can find information on both of those.
There’s also a Chinese Corner every Wednesday in Chengdu that started recently, that’s worth checking out.
I would give formal lessons a shot and see how they work for you. Personally I’m better off self learning but I’ve published some posts on the topic of learning Chinese in the post series section. Good luck-