My breasts appear to be a lot smaller than I wanted, will they fill out a bit more?

Try not to focus on how things look immediately.  Your breasts will change a lot as you recover.  You've been used to large breasts for a long time & thus it will take some adjusting to the new size.  Give your body & mind time to adjust.  All the best Kim

It is difficult to assess results only 48h out from surgery.  Go to your follow up appointments with your surgeon and discuss.  There is always an adjustment period after having surgery and you may become more used to the new you over time.  

Hello dear! Thank you for the question,Allow the tissue to heal and wait at least two months to start seeing the real results. Yes, it is possible they will settle down and fill out more to the size they should be, it is still early to see results. In case you have any significant concern, reach your doctor out.Hope you get results as expected!Dr. Jiménez ToribioPlastic and Reconstructive Surgeon.