Slow drain

I am installing a shampoo bowl backwash system for a hair salon. The problem I'm having is that I have a slow drain. Unfortunately the pipe from the sink that I attached to the p-trap is kinda long. It does go downward first but the it turns in an almost 90degree angle and goes to the p-trap. Unfortunatley it's a bit in an upward angle so the water draining slows and backsdown a bit so therefore gravity is not doing all it can do. I wish I could post a picture of it but I can here. If anyone has any ideas I would gladly email you a picture. My email is bsondi@cfl.rr.com. I would appreciate any ideas and input. I also was wondering if I could bring down the p-trap about a few inches lower than where it connects to the wall so I can have a more of a downward flow to the p-trap from the sink so gravity can do its work? Please help asap. Thanks in advance.

I would lower the drain pipe in the wall. Also would extend the drain pipe with the trap adapter as close to the sink as passable to be able to properly install the p-trap.

The p-trap is also on backwards.

In many areas this work would need to be done by a licensed inspector and have inspections by plumbing and health inspectors...