New to SAD

I came out of work today, and for the first time in ages, the sun was still out. Driving home, I realised that I haven't felt this happy in months. I have been quite low, grouchy, and sometimes quite angry for months. I know how I've felt, but I just didn't connect to it, I've just been stuck in a rut.
The last time I remember being truly happy was last summer. Then it came to me, maybe it is this seasonal disorder thing that I vaguely heard about somewhere once upon a time. I have always had problems with my mood, went through depression as a teen, and pondered whether I was bipolar at one stage as sometimes I felt on top of the world....but then crossed that idea out cause my "happy" stages didn't really last for that long, and from what I read about it, it didn't sound quite the same.
But reading about SAD sounds so familiar to me. The past 2 months in particular I have been bingeing on food more at work and I couldn't figure out why, cause I've never been a big eater. My partner and I have both been arguing alot, mainly cause I haven't got the patience for anything and am extremely irritable.

Does this sound like SAD? I don't want to go to a doctor to find out, as in my past experience, they are clueless about mood disorders.

Thanks for reading