Hi Caroline, my experience is that they are ok being pot bound (small pot - although I planted mine in 5 inch pots - once they were large enough) You're right as the sun gets stronger they'll prefer a east or west facing window, for you in Calgary, that seems like it won't be for a few months. Also it seems they prefer cooler temps (for me I didn't know this, since Seattle stays moderate in summer :biggrin:) and also I keep my house cool (ish) in winter so I guess accidentally I'm providing them with good conditions
One important thing is that I feed lightly with each watering - 1/4 strength of whatever plant food you use (I use liquid Shultz plant food)
Streps do go through a dormant period but if feeding and in the right condition they should be blooming again soon
Can't wait to see photos!