How to not feel somber during this winter?

Every year i get this saf lazy somber feeling that turns into depression. Now I have a hiuse I love, a baby I love, a fiance I love, and I'm starting to getcthat feeling again. I dont know how to pull out of it. My daughter is constantly tored since i started feeling thos way, ive been neglecting thibgs i should do, im soxezhausted all the time. What I'm asking is how i can get out of this feeling before it turns to full blown depression. Im at home woth baby from 8am - 7pm alone everybday. While fiance is at work. Me and baby go to swimming lessons, play groups, basically anything to get out of the house. But its just not enough. Im stuck on thos rut.i have thought of anti depressants but they always make me really really sick. I dont know what to do. I wanna be a happy mommy and fiance, but im wrecking it.