I've achieved a big milestone recently. Up until the last few months my significant other(a native) would never speak mandarin with me. When I first started, I pushed it but she wouldn't budge. I let it go and decided not to push it anymore. Still had her mother to speak Chinese with.
As I've improved, expanded my vocabulary, grammar etc, I casually - even accidentally would slip in some mandarin and she kind of naturally started replying in mandarin. It has happened quite naturally. Lately she's even been starting conversations with me in Chinese sometimes. Also, if she says something in English to me that I want to hear in Chinese or that is well within my understanding, I say "再说一遍“, she's a good sport about it and says it again in Chinese. Other than that, I'm still not pushing it. I also don't bother her with grammar questions and the like.
Right now I suppose it's 25 percent Chinese 75 English, but a huge change from zero. I'm sure as I continue to improve my skills the percentage will shift further.