I have started to do yoga on days that I'm not strength training. Since yoga is a form of strength training, am I doing too much if I alternate yoga days with weight lifting days? I like to do at least 2 yoga sessions per week and 3 weight sessions per week. How should I schedule the sessions to get the proper rest?

Yoga is a great form of exercise, and is training many different muscles. If you and your muscles don't feel overly tired on this schedule, then what you're doing is just fine. But if you experience fatigue or find that you aren't able to progress, consider doing the yoga and strength training on the same day so you can allow a rest day between workouts.