I grew up speaking German and Flemish ... but lived in the USA. My parents emmigrated to the US from Germany two years before I was born. I didn't start learning English until I started school at age 5. As a result, I don't have an accent in any of the languages. Having no formal education in German or Flemish however, my language skills were not so good. I studied 4 years of German in high school and another 4 years in college ... which helped immensely. My Flemish however, is still rudimentary.
I found German to be more useful when I lived in Germany for 3 years ... not so much now, except to speak with family members. I also worked for a few years translating historical books from German to English. I would probably gain more in my present location through learning Spanish. I do speak a little of that, but only a very little. I speak Flemish only with my mother, as all of the more senior members of my family who spoke it have since passed away.
English is my primary and best language. German second, then Flemish and Spanish. I find writing German to be the most difficult, as it requires the most precision. I cannot write in Flemish or Spanish at all.
I chicken out all the time due to lack of confidence in my ability to speak languages properly