K.S.
I feel for you...really. I have been struggling with mood swings ever since my first child...over 5 years ago at age 34.
I think 'peri-menopause'(which can start in the mid-30's) and birthcontrol products contributed to my problems. I was on Depo Prevera, then IUD Mirena (which fell out within 3 years) then started Seasonale (the 3 month pill)but only took it for 2 months. The breaking point was while I was on the Seasonale I had a SEVERE mood outburst and had extreme suicidal thoughts. Obviously I didn't act on it but it was very strong and scary. (By the way my vision changed too. Seriously. I needed glasses when I had never worn them before. Since I stopped the pill I no longer need to wear glasses...my point is sometimes medication can have side effects you'd never imagine.)
Well I stopped taking any BC in November and feel SO MUCH BETTER!!! I still have some moodiness but it is not as extreme.
Around the same time I stopped the BC pill, I started taking thyroid medicine...Armour Thyroid...which is a natural version.
I suspect your moodiness is hormonally related. But it is best to talk to a doctor. I warn you, they'll probably suggest an anti-depressant. If you are not up for that sort of therapy, I suggest going to a DO/Homeopathic/Naturalpathic doctor.
I live in the Cleveland area and just started seeing someone here (which is why I started the thyroid med.) My blood work came back 'sub-clinical hypothyroidism' which is not normally medicated by mainstream doctors. But my doctor said that low thyroid contributes to a lot of problems.
Check out the book "The Hormone Survival Guide for Perimenopause: Balance your Hormones Naturally" by Nisha Jackson. I think it might provide some help.
Best Wishes!