To sleep or not to sleep?

As I've mentioned in previous posts I really struggle to get to sleep at night and some nights I don't sleep at all. Insomnia is real.
I spoke to my GP about the issues I was having and everything I had tried. This included staying off electronic devices before bed, burning a lavender candle, pillow spray, listening to sleep stories, reading, having a warm milky drink, herbal teas, mindfulness. Nothing seemed to work. So my doctor said she would prescribe me an extra antidepressant to take at night which would help me sleep. I would try anything at this point! My prescription was for 15mg of Mirtazapine.
Sure enough, the first time I took one I was out like a light and slept for 11 hours straight, but I woke up feeling groggy and out of sorts for the rest of the day. Gradually, I've got used to them and am now sleeping between 5 and 7 hours every night.and not feeling groggy once I've woken up.
After 6 or 7 weeks of taking them my clothes started to feel a bit snug and I was feeling uncomfortable. I know I shouldn't have, but I stood on the dreaded scales of doom and was horrified to see I'd put a stone on in 6 weeks! WTF?! How the hell had that happened? I don't think I'd been eating any differently and certainly not enough to put that much weight on in such a short space of time!
I was due to see my GP for a review and decided I would talk to her about it as it wasn't helping with the way I was feeling. Meanwhile, I googled the side effects of Mirtazapine and right there at the top of very common side effects was weight gain. I looked at a couple of patient discussion forums and it was, indeed very common, with people reporting to have gone from a size 10 to a size 16 in 3 months of taking the tablets.
When I saw my GP I didn't even have to finish my sentence, she knew I was going to say I'd put on weight. She said she could put me on Quetiapine instead but that wouldn't help me to sleep.
So I can either sleep and be fat and uncomfortable or lose some weight and not sleep! I said I'd have a think about it, which she said was fine and if I did want to change meds I could just contact the surgery and she would do a prescription for the new ones.
I thought about it for a week and decided that if I was going to come off the mirtazapine it was best to do it while I was off work. I rang the doctor and she said I needed to wean myself off them first. I have to take one, then miss a night, take one, then miss 2 nights and so on. I'm on night 6 and I'm going to be honest and say I've been struggling on the nights I haven't taken one. and during the day today I've felt anxious and jittery. But I will persevere.
I know I shouldn't let my weight bother me, but I need to feel better about other aspects of my life in order to feel better about my size and weight. And it is something that has plagued me my whole life.....