There is nothing necessary between Photo-Session 2 and 3, and both sessions start on saturday at 10:00 (instead of shopping). There are 3 conditions.
1.
lenter>0 - that's the same for PS 2 and 3, so it should be ok (you've had already PS 2)
2.
eric.inf=7 - is set at the end of PS 2 to the level 7, also you should have it, and
3. lizamood>349
then you get following choice:
Ꚛ Look if she's ready for next round (see picture 1)
View attachment 69794
If you still cannot start PS 3 try to cheat it: open your laptop, go to Galin's cheat menu ->cheat Lisa -> Reset Lisa Photo-Session -> You have there the chance to reset/change the counter eric.inf to the different steps ot PS 1-3 (see picture 2)
On left side (right to the emo-image), you can see current status, and change to desired.
View attachment 69795
Yeah, I've seen the restart of the clinic event too, but I think that might be a bug, because I've got it also in normal, unmodded game sometimes.