Chances are the tiredness will go away once you are stabilised on 30mg. I felt like I had swallowed an earthquake and had to go back to 15mg.

how about 5 weeks? is that very short aswell and can i just stop taking them

yes three weeks is very short! and please ask your doctor for something else. there are meds thatbdon't make you this tired

I’ve been prescribed Mirtazapine for postpartum depression/anxiety

I was advised to take 15mg for 2 weeks then upped to 30mg. I’ve now been taking Mirtazapine for a total of 3 weeks. I simply cannot take the tiredness anymore. I have a newborn to look after and cannot wake up to tend to her. 

I have 14x 15mg left. How would you taper?

Tapering/stopping