Medication adjustment and menstrual cycle?

Hi there. I would love any insight into this.

I am schizophrenic (and then some) and I take five different meds each day. (I can list them if anyone thinks it would be helpful info.) There have been two times in my life where I adjusted the meds and had a BAD menstrual period afterward.

The first time, I asked my doctor if I could try taking Trazodone for sleep again. He prescribed it, I tried it, it didn't help me sleep, and after about a week, I gave up and quit taking it. (We're talking low doses of it that wouldn't require tapering.)

My next period was pure hell. My hormones went berserkers.

Recently, on New Year's Day, I went up on Zoloft from one pill to one and a half pills. I had asked my psychiatrist permission, because I get bad SAD every winter. (Seasonal Affective Disorder.) About two weeks later, on January 15, I became a raving lunatic for the entire week of my period. It was awful.

Now, winter is ending, and at any point, I can go back down from one and a half Zoloft to one Zoloft. Needless to say, I'm scared to do so.

Here's my question: does anyone know which phase of the menstrual cycle is the best time to make a medicine adjustment? I know that halfway through is the wrong time, from my above example. So would it be best to do it at the start of your period, or perhaps at the end of it? And does anyone else have any experience with medicines affecting your hormones and menstrual cycle this way? Any info welcome. Thanks!