DD 2.1 unsettled since starting preschool

[Yeeyeelovesraaraa]

DD (2.1) has just started at preschool one session/week. She's had 4 settling in sessions so far but since starting has become extremely unsettled & clingy at home, crying all the time, becoming very upset if I leave her (even if its just with DH while I nip to the loo) & keeps saying I not like preschool I not go to preschool.

I sneaked off the first time I left her there as I/staff felt it was the easiest thing to do but with hindsight I regret doing it as think now she is constantly worrying i'm going to disappear whenever her back is turned. On her latest visit I did drop & go - she was very upset as I left & although settled quickly & they said she was fine she's been very quiet & not herself since coming home.

Would you take this as a sign she's just not ready for this kind of setting yet? I don't know if I should give it a few more weeks to give her more chance to settle or call it a day & wait til she's a bit older.