Best lens for natural light indoors?

[Alyssaran]

I have an 18-55 kit lens which is doable, and a 50mm f/1.8 which I absolutely love, but seeing as most of my photography involves nude or lingerie portraits in a small bedroom, the zoom is often way too close for me to have a variety of angles. I love the low aperture for the overall look of the photos, as well as the benefits in low light, as I usually shoot in a room with a large window and use only sun lighting, but the zoom is making it hard for me. I'm a student so I really can't afford a 35mm at the moment. What lens do you guys use or reccomend for a canon rebel under these settings??