In this paragraph:
ちなみに私の語学力は日英ほぼ同レベルだけど、会話だけは日本語のほうが得意。つまり日本語力の問題ではない。仲良い友達も日本人が多い。英語という逃げ込む場所があるから違いが身にしみるだけで、もし日本語しかわからなかったら自分は人見知りなんだと思うだろう。
My interpretation of 身にしみる is for something to really penetrate through to your heart. Something you think about deeply or 'touches home' (jisho.org)
My translation of this paragraph is something like:
Incidentally, my Japanese and English skills are about the same. Only at the conversation level is my Japanese better. Basically, it's not a language problem. I also have a lot of close Japanese friends!
Here's where I trip up. The last sentence has three components that I really can't put together:
- Since I escape to English
- Just from really feeling that difference
- You'd probably think I was a shy person if I spoke just Japanese