Feeling like the world's worst mom :'(

I just took my almost 2.5 year old to her second pediatric dentist appointment and found out she has three biting surface cavities in her baby molars...  Three!!!  :(  We brush every night and most mornings... I am crying even thinking of the fact she has to go through getting three fillings and they couldn't get her an appointment until Aug. 31st!  I'm #1 on the waiting list for cancellations but I am about to have an anxiety attack :(  The thought of her having mild sedation makes me nauseous.  Has anyone experienced cavities with kids this young?