Risotto is VERY tricky to make. Firstly, 90 minutes? That sounds 60 minutes too long to me!
The mushrooms, if you use them, should either be cooked separately and added to the risotto last, or added very near the end.
Mushroom taste is very overpowering, and risotto soaks up everything around it.
The joy of risotto is that it can take 10+ times to get it right, but when you do oh how GOOD it feels!