It's hard to tell from a photos but it simply looks to me like it's getting pretty dry and you need a trim on the ends. You MIGHT (depending on the thickness of your hair, I honestly think with fine hair layers are not a great idea, at least not on mine) want to get a few long layers around your face just to style it a bit more.

I don't think it is product buildup because I think eventually ALL buildup will rinse or wash out, but chemicals do permanently enter the hair shaft. All we can do is deal with the outside, and I don't think trying to strip it out will help the condition.

If you do a deep conditioner, make sure to rinse it all out and don't use heavy products on your hair, or anything with alcohol or silicones. It looks as if it's getting weighed down. I would use clips in the top as well and let it airdry as often as you can.

Just my two cents -- take any of this you think might work for you, and good luck!!

And P.S. Stress can thin your hair out, and you may lose more hairs at some times of the month than others. Try taking some Biotin, it may help.