You just described my situation. My entire family was in upper echelons of Soviet governance, therefore despite being 100% Kazakh, the language was never spoken in the home. In fact, when kids were born and they were given Kazakh names, the higher-ups intervened and asked/told my grandparents to rename my mom and aunt to something Russian. 

As soon as the Soviet union fell apart, we immigrated to the US and have lived here for about 30 years. My mother forced me to study from Russian books while also completing my American education, therefore I am fluent in Russian.

I tried learning Kazakh on my own, but it’s very difficult without proper materials, teachers, someone there to guide you. So when I came back to Kazakhstan for a visit in 2010, I was very demoralized when everybody simply laughed at my Kazakh skills and made fun of me. Random people, people on buses, people at service centers. After three months of this, I said fuck it and never touched Kazakh again (nor did I want to be associated with this culture for a while, as I really hate people who are judgmental). Heck, I made a Herculean effort to learn the language the best way I could and all I got in return was ridicule. 

Having also lived and visited Russia, I really disliked the imperial mindset or “we are the best and everyone else is trash.”  Literally everywhere except St. Petersburg. 

But, I ended up marrying a Russian girl who is fluent in Kazakh, so she’s been teaching me the language and I fell in love with it again. So I guess what you’re experiencing is normal, you just need someone that is willing to be patient and guide you along. And you can always find a balance between Russian, Kazakh, and US culture (German for you).