Breast reduction post op

I got a breast reduction about 5 weeks ago. 3 weeks in a tried on a bar and bought a bra that fit perfectly. Now I'm 5 weeks post op and tried on the same bra and it is too small now. I also haven't gained weight, if anything I've lost weight. I thought mayb it could be that I am getting my period soon so my breasts are inflamed but they've been this size for a week and I haven't gotten my period. Does anyone know what this could be and if it is temporary?