depressive periods

I wouldn't consider myself clinically depressed. I have a background in psychology and I know the symptoms. However, sometimes I get really depressive thoughts and feelings. I think that my friends don't really like me, I don't have a drive to do anything and I feel worthless. I realized that these feelings are cyclical and they can occur right before my period. I know some women get emotional before their period but these feelings are very intense. I remember when I was younger just crying so hard because I felt like my heart was broken, but in actuality there was no legitimate reason for those feelings. I still get them every now and then and I am a generalized anxious person but I was curious if anyone else had that? I don't always have this, usually in the winter (maybe has something to do with the winter Seasonal Affective Disorder) but I'm feeling really down in the mouth right now...wondering if anyone else experiences this?