Coolant Leak - help me

[Bouchedag84]

Hey guys

Last Thursday my 2006 4.4i notified me to check my coolant level. I did, so Friday I went to BMW and got the coolant.

Anyways,
Friday 4pm: topped up the coolant reservoir with 50/50 mix of BMW Coolant and distilled water, engine cold.
Friday 7pm: parked the X at my girl's house for the weekend while we camping
Sunday 3pm: arrive back at girls' house. Drive X around for a bit (~35mins) doing errands and park it at my house for the night at around 6:30pm.
Sunday 8:00pm: check coolant level in X and it is about 1/2" lower than what I topped it up to. Look under X and this is what I find.
This picture is taken from the passenger side looking towards the drivers front wheel.

I am assuming it was leaking from this drain pipe, is this the A/C drain pipe? If so, is this normal for this amount of liquid?



Am I being too paranoid?
I am really worried about the bimmerpipe issue or a leaking valley pan, however, I do not know how to diagnose this. I plan on doing a few longer road trips with the X but I don't want to seize my engine or anything. Obviously, I'll keep a jug of coolant and distilled water in my trunk but still, I don't want to have to constantly worry about it.

Thoughts/suggestions/diagnose this for me, please!
Note: I have 94,500kms, I have not seen any actual coolant anywhere beneath the car. Only the low level in the reservoir and the notification on the instrument cluster have alarmed to the missing coolant...

Edit:
here is the bottom of my engine filler cap

and the bottom drivers side corner of the coolant expansion tank - kind of feels a bit greasy where i've circled in red