If he already told you to go back to the 150 I'd say do so right away and see how you feel.

Don't assume that he intends to take you off it entirely. If he does intend to take you off of it tell him that you really think that the 150 is doing well for you, you feel better on it, and would like to give it some more time to see if you improve more just on the 150.

People react very differently to different doses and if you think that 150 is really helping you, make sure you make that clear to him... if he still wants to switch you to a different med, ask him to explain why, since you feel like the 150 is working successfully. He may have good reason, but he should be able to make you feel comfortable with the decision at least.

Good luck, I hope you can get some relief over the weekend.