Citalopram not powerful enough

Ive been on Citalopram (celexa) for a month now as I suffered from very severe depressino and anxiety and am very soon getting behaviour therapy. The citalopram has taken some of the edge off the depression but it feels as if its just surpressing my feelings and stopping me letting them out. And i still have anxiety attacks quite frequently and have to force myself to do almost anything during the day as I just want to hide under my blanket all day. So Im thinking of changing to a different one, maybe one which is more powerful or to see if a different one will work better for me like prozac or something.

I was wondering what you do when you change SSRI's? If I was going to change to prozac would I have to get weened off teh citalopram first then start taking teh prozac? Or could I Just switch them over immediately?