How to stabilize my sawtooth oscillator
Isn't that circuit in your picture supposed to be supplied by a symmetrical +15V and -15V supply?  In that case it will need some adaptation for a single supply. 
The transistor you are using can also have a threshold up to 3V, so you might not even turn it on with a 3.3V supply only. 

MAybe this topology helps https://www.maximintegrated.com/en/app-notes/index.mvp/id/4362