Oil leak - Octavia 1.8T AUM

Hi guys,
It's me again, couple months ago I've replaced the rocket cover gaskets on top as was having oil in the spark plugs.
However I've noticed still I have to put some oil in the car for example 100-150ml per 500-600km.
I've inspected the spark plugs and top of the engine no oil leak.

But on the bottom side will have to remove the plasic cover under the engine, but on the right side it seems to me like the leak.
Any suggestions on this?

I drive with 5w40 oil, but push it from time to time when accelerating  
Also no smoke while driving or on starting, what I have noticed is that when the car is warm, sometimes it struggles to start from the first or second try (it has an lpg system) but when hold cranking it longer it start
Thanks in advance!