You(and we all) are earning money that we don't legally have. A trouble if you want to withdraw for large expenses, but THEY won't be able to take it from you because you don't have it.
Solutions: withdraw slowly and don't have a lifestyle much bigger than you could have with your "legal" sources of income. Or gain much more by other ways, so your Bitcoins earnings could pass by without being noticed
What you say is absolutely correct. We do not have any information regarding your identity and your Bitcoin account so we can not prove that it is legitimate, and of course it is not legal. So your solution is the best solution. It will make the bank pay less attention to you