You're not facing this problem alone, there are too many Blockchain.com wallet users that brought up their problem here related to yours.
For example, this thread is most likely the same as your problem,
Transferring from trading wallet to wallet? Blockchain. Com, or scroll down on this board and you will see different issues towards that Bitcoin web wallet.
Yeah, you need to wait more or less 7 days for the transaction to be confirmed, it shows insufficient funds because it was already transacted.
I think you will have a lesson to learn from this and give you a reason not to use again this wallet if ever you decided to transfer your fund, I suggest this wallet,
Electrum. It's free to download and make sure to verify the official website first before you download, it better to have full control over your fund.