Is this normal?

Yep single right side masectomy at least 6 to 8 wks of tightness . You must do what exercise you can even if its only shoulder rolls. When you can massage the chest wall get physio to show you how to do it properly. Infection makes it bit tricky take it easy dont expect too much too early a little bit goes a long way. Dont rush you are allowed to feel sore and tired just take the time to heal. Take all the time you need. Pure rosehip oil helped the scar after no infection just dont be too hard on yourself  take the time you need to adjust.