I've decided that "the very low end of normal" on thyroid is stupid. They need to change the "normal." Because in college, they said mine was on the very low end of normal, so they didn't put me on anything. After another year of going to doctors, they decided I have fibromyalgia. I dn't really doubt the diagnosis, but I recently read one fibromyalgia specialist who discovered that most of his patients' thyroid levels are on the "very low end of normal." He puts them on meds and BOOM, they start feeling lots better.
That would help with your hair loss (which I'm having right now, too--it's nuts how much comes out! Not the normal amount), weight, and I don't know if you have low energy or dry skin, but those are all happening to me.
Hypothyroidism also effects monthly cycles, so maybe it's tied in to your spotting? When you go to the endocrinologist, speak up about your low thyroid. Ask if he can put you on a low dose of thyroid replacement. I've learned that most of the time, doctors ignore symptoms that people don't really speak up about. From their point of view, it totally makes sense--they focus on the big problems. From our point of view, it means we have to speak up and don't let them decide which symptoms are most important.
Good luck!