This is way out in left field, but you mentioned vitamins and herbs etc, so it came to mind
first, I have to say that regardless of what effects your period brings, your body was made to be on a cycle for a reason, you were born that way, as was every other woman (even though it varies from cycle to cycle and woman to woman) and there are certain things that will interfer with that cycle, but you were born to have it, never the less.
If you have really bad symptoms of pms you should definitely consider trying to take care of them (i'm just clarifying my first statement to let you know i'm not a "suck it up/grin and bare it" type person. However, forcing your period to never come really messes with the natural process of things. Besides that you're pumping your body full of extra things that it doesn't need, primarily, estrogen and hormones. Those extra hormones flying around your body cannot be processed by your liver and are called xeno (zee-no) estrogens which can be toxic (why almost every woman on birth control when it was first introduced decades ago got cancer). The extra estrogens that can't be absorbed attach to proteins (namely tissue and muscle, like your cervix) and cause those cells to mutate (because those cells aren't supposed to have hormones attached to them). Bad stuff.
Also, it is possible because of your diet and exercise (i have no idea what it is) and from being on birth control for a while, and maybe even just hereditary, that you are beginning menopaus (for all these reasons women are beginning menopause ridiculously early now). If this is the case (and even if it's not menopause, it could be something else) it is entirely normal for you to have depression and other hormonal symptoms that are hard to deal/cope with.
So my question is: have you ever considered doing a detox (like a kidney/liver/etc.)? Even from eating a lot of fast food and usuing house hold cleaners over the years, your body stores toxins and if you don't habitually drink enough water, exercise enough, eat the right kind of foods, your body can't really expel those toxins and that leads to a whole host of problems in your body: pms symptoms, ms (multiple sclerosis) symptoms, depression, digestive problems, headaches, etc. Etc. Etc.
Like I said, it seems like way out in left field, but you should consider a detox and maybe changing some eating/exercise habits and see if it makes a difference (by the way, i'm not saying this is the end-all, cure-all for depression, but it's definitely an option to consider before diving in to a vertigo spinning world of hormones and drugs).
Ps-did you know that premarine, the leading drug for hormone replacement therapy, is composed of hormones taken from pregnant mare's urine? Pre-ma-rine. Wow, cool, ingest horse pee.