I have a Taiwan-born American friend, whom I met here in Taiwan, who has a similar situation. He and his parents moved to the U.S. when he was 8, and he’s lived there for the past 35 years. His parents have since moved back to Taiwan to retire, and he comes here a couple of times a year to visit them.
He can speak Mandarin without much of a foreign accent, but his vocabulary is stuck at an 8-year-old’s, and he can’t read Chinese. It gets frustrating for him to have to continually explain to locals why he looks and sounds Taiwanese but can’t hold an in-depth conversation, and would rather speak in English (He uses mostly English with his parents, although they’ll often speak to him in Mandarin). I think sometimes local people assume he’s trying to show off, but it’s just that he’s more comfortable speaking the language he’s used for the past three decades.
As for being social in English, you might check out Meetup.com. They have a lot of weekly events in both English and Chinese. Good luck with your move.