Hello Nico! What are your temperatures outside during the Spring and Summer? If it is warm enough (I see you are in zone 3) you can leave your semp outside for those seasons and then put back indoors when it is really cold. Spending most of the time in the brightest room indoors may mean there's not enough light.
If you do decide to move outside, do it gradually over few weeks so that plant can acclimate to the change.
Maybe somebody else on the forum can advise on the possibility of your semp being able to survive outside all the time. I'm not sure what very low temps semps can be hardy to.
