There are many meds besides Seroquel. Seroquel did not work for me either, i.e. it didn't prevent angry mania even in doses much much higher than yours. Tell the doctor that you are sad all the time and your husband does not recognize the old you in this sad woman. I believe Seroquel cannot be stopped cold turkey, but since you are on a small dose, tapering off should not take a long time.

Even though the dose is small, had this medication been effective against depression in you, the effect would have kicked in by now. I do not see a point in increasing the dose.

Don't make a judgment on the meds' effectiveness based on Seroquel alone; treat it as an outlier.

My guess is you need a combo of a low dose anti-depressant with a mood stabilizer or a neuroleptic (what is called anti-psychotic in the US). I do not think you would go far with a neuroleptic alone, given the pervasive sadness. Seroquel is a neuroleptic. Anti-depressants alone wouldn't work either as you already know.