For those who don't speak German, for transistor 1 lambda is 0, but not for the others. The backgate-effekt should be neglected alltogether.

I drew the following small signal equivalent circuit (ignore the black texts for now):

This should be fine, I got the whole 7% for that part of the exercise.

Now, my question is the following: are my calculations correct here? :

I don't see where I am wrong. I got 2% and 2% instead of the 8% and 10%, so 4% out of the 18%. But as far as I see, I only had two problems in my calculations, I accidentally took vgs2 with positive sign (bad mistake, I know, I drew it correctly, but still got the wrong sign), and in the current calculations I should have added the gm3*vgs3 current because of the direction, but I subtracted it by mistake (again, the direction was drawn correctly, yet I made another mistake).

In these calculations that I posted, I recognized these mistakes and corrected them. The question is, is there something else that I am not getting here? Still some currents in the wrong direction? Some wrong calculation? I did not get any solutions, I only got a comment, saying: "current flows towards source, and as for PMOS, per definition negative". And don't really get what this means, I wrote to the tutor but it will take some time for me to get an answer and even if I do it probably won't explain my mistakes properly.

The mistakes that I found are bad mistakes, I get it, but I don't think that they are worth 77.8% of the exercise, so there must be something else. Also, this comment must mean something that I don't yet understand.

All help and explanation is appreciated!