AdamB
When should alarm bells start to ring??
In principle - When you hear them
As I've said many times before, there is nobody here can tell you what to do.
You have to make the decisions.
No offence Adam, but there are plenty of posts very recently that should help you.
If this young lady is a scammer she has no intention of putting a gun to your head to rob you. You will just give whatever of your own free will.
No dark alley in cyberspace.
Maybe she's just playing you for small fun. P3600 is not so much to lose. If you are a gambling man maybe it's worth it to see her hand.
Maybe she is really a genuine, hardworking respectable lady who will make you happy the rest of your life.
Adam, I would urge you to read the other posts. Decide you next move and just do it. Be always aware of your own feelings and be prepared for anything.
Sorry, I'm not much help.