Switching to citalopram

hi I have been on mirtazapine for 2 years at 37.5 mg. it has helped but not as much as I would hope. and I am still tired through the day.

I took citalopram previously and it did the job, although it took a while to stabilise, 12 weeks so am going to ask my Dr to switch me over. it is likely to be a longish cross taper 6 weeks.

has anyone experience of this how was the process.