I've seen plenty of self harm scars but this girl has both arms and legs covered in them. Her mental health issues obviously run pretty deep. With the added alcohol and the emotion of being turned away from the club while her friends gained entry and were having a good time, it is possible this has made her do something to herself.
If she had fallen or injured herself, it's likely she would have been found by now. If she purposely went to harm herself, I believe unfortunately, she would head to the drain area. Yes this area has been searched but it's just too large to be conclusive right away.
People do not like to mention this mental health aspect and would even deem others bad people for mentioning it but it could be a vital part in this so it's dangerous not to bring it up. The other scenario of foul play by a stranger seems very rare right now for this area.
Screams are heard all the time regarding that and a fox also makes that horrible like scream. I have to say it, with no further evidence and this many days in, it seems highly unlikely this girl is going to be found safe and OK. Do her friends confirm she didn't have her phone out with her? It seems unusual she wouldn't. I can only imagine she perhaps lost her keys which is why she didn't enter her residence and she had no phone to call anyone, but then she said she was OK to the passer by. It's all very strange.