Vitamin D 5,000 IU/d and a light box will do wonders for seasonal depression.
Dating and mom friends - both do require effort. But it's important to put that effort out. I'm a friendly introvert (I'm not shy, but I need my alone time to recharge). When I was married, my extroverted ex-husband would arrange dinner parties and camping trips with friends (the friends HE liked, he was intolerant of spending time with anyone HE didn't enjoy).
I didn't keep in touch with those friends after the divorce (honestly, most of the women were gossipy - not my thing).
I have one super-close female friend, that I've known for thirty years. We talk almost daily and lunch together a couple of times a week. And I have casual friends that I see occasionally, but as I get older (61) I can see that my laziness in this arena is a bad thing. I need a bigger network of close friends - the happiest older people that I have seen were ones that had an active social life with a group of friends that they had for years. I also see how my 85 year old mom has outlived her few close friends and all but one of her six siblings, and how her shyness has kept her from making new friends.
So one of my goals going forward is to work harder on broadening that circle of good friends, and try to create a more sustainable long term circle of good friends. Towards that end, I'm starting a "goals group" with my friend and some other women - kind of like a deeper bucket list. Not about one-off items like skydiving, but big picture things - what have I not accomplished yet in my personal, professional or financial life, that I would like to? How do I prioritize those choices? And how do I begin to manifest them in my life?
What kind of group might you be interested in starting?