Is the phrase 'less boys' correct?

No.

You would need to use "there are less boys than girls in the room". Clearly that is incorrect.

Instead use "there are fewer boys than girls...".

Hope this helps.

you have three options. first, you can delete the instagram account. two, you can change the handle, username, and profile photo and make the account private. finally, you can just confess. there really is no point in lying to them.