I do feel for you, I get a sort of winter depression and I get migraines.
I live by my SAD lamp, so I would suggest you see if there’s anything more that can be done to help your migraines.
I was just reading this morning that a diet high in Omega 3s (fatty fish) and magnesium can help. See your GP if there’s anything new on the market that you could take. I’ve even read that having an orgasm can release chemicals that relieve a migraine! You say you live alone, but a vibrator can be a good substitute.
As a migraine sufferer I know that you know your body and what’s sets them off - but I’d suggest trying the sad lamp again. Maybe start it further away and in shorter doses, maybe wear sunglasses, or cover your eyes.
As suggested get outside - but try somewhere or something that really hits that dopamine spot. I used to have a dog and a small wood nearby - a walk in the woods when it was snowing was magical. I now find it hard to summon the motivation to get outside during the winter without my dog (she died of old age a few years ago), but I know it’s good for me.
I also rent and am not allowed either cats or dogs. However last year I joined Trusted House Sitters - you go and house sit (for free) in another persons home. That way you can still work from home, but have the added company of a cat/s or dog/s and you will have to go out to walk the dog. I used to go to places that were in more lovely areas than mine. Novelty/variety in your life is needed if you are like me and live a very quiet, routine life.
I also take antidepressants and also found weight gain/apathy were side effects. I thought I’d tried most of them, even some of the older tricyclics which often have more side effects eg Mirtzapine termed me into a zombie. However after deciding to wean myself of my current SSRI because it just made me feel ‘meh - whatever’, I had a shingles type nerve pain. My GP put me on Amitriptyline and mentioned it was also an older style antidepressants. My nerve pain went, but I felt so much better that I’m now taking it regularly. I’m so surprised that a really old antidepressant suits me so well.
It’s all the usual things that help - good sleeping habits, some regular exercise, good diet. I also take Vit D supplements much of the year.
I’ve read that we need social connectivity, meaning and variety to keep our mental health steady, I now live by the phrase ‘stay busy, be useful’
You are very wise to start thinking about this now, because once it creeps up on you - it’s very hard to find the motivation to do all these sensible things. My biggest problem is anhedonia - where you stop enjoying the things that
you normally enjoy. This of course sets up a vicious circle - you feel miserable and unmotivated, so you do the minimum to get through the day, which means the next day you feel the same (or worse) so do even less.
You are in a difficult situation where you can’t change much to put yourself in a different situation- can’t use a sad lamp because of migraines, can’t get a dog because of renting. This must make you feel very powerless, and I know from personal experience feeling helpless in a situation makes things worse.
I hope that something in one of the suggestions from all the posters helps you.
Oh and by the way, Trusted Housesitters covers overseas places as well. It’s not as busy as in summer, but there’s always plenty of pets sits over Christmas and New Year.