Most women find that postpartum hair loss starts around six months after giving birth. Some go through it earlier, while others notice strands of hair in their brush a lot later. I remember it all too well myself hairs were everywhere in the bathroom, the sink, the bath tub, and even in the washing machine. It looked quite dramatic and if you'd seen all those long black hairs, you would have thought you could make a wig out of them. For a moment, I thought I was going bald. The truth was thankfully a lot different! My hair still looks pretty OK now, two and a half years after my second child was born, and I don't look like someone suffering from male pattern baldness. You will mostly likely have the same experience as well.
Your hair might seem like it is seriously thinning but all it is is doing is going back to its former self. And of course, it looked just fine before you got pregnant too. Women who have very long hair are much more likely to notice a big "fall out" (yes, points for the cheesy pun!) during the postpartum period than women with short bobs or shorter hair. In any case, postpartum hair loss will not last forever, so you don't have to worry about it.