I've been obese all my life and a yo-yo dieter so my weight has fluctuated from 10st (doing VLCD) to 21st.
Even now, having done SW for over a year and a half, my head still hasn't caught up with my body. I'm 11st 11lb and still feel like I'm in the 15's if not the 17's! I look at people who are 15 or 16st and still think I'm the same size as them.
It will take time but eventually it will all fall into place and your head will get used to the new, healthier you!