Are you still taking a prenatal vitamin? The hair loss could be vitamin/mineral deficiency related but it might be worth talking to your doctor just to be sure it isn't something else. As you know some hair loss is normal as your hormones balance out. If it seems like too much, talk to the doc.
If you think your supply is down, maybe pump and see what comes out and then feed the baby from the bottle. Supply may not be down, it just might feel different as you and your son are more efficient at nursing.
Adding in pumping, extra nursing sessions and doing a diet check will help get your supply up. Eating whole grain oatmeal, drinking dark beer and also trying mother's milk tea will help too. Do a google search for increasing breast milk supply and you may get a few more tips.
Also, if you've started to diet to loose weight, you should only be loosing a pound or two a week - any more will compromise your supply and milk quality. And don't overdo it on exercise as that too can affect supply. Drink lots of water - I find if I'm not drinking at least 3 liters a day, my supply drops.
Not having a period this long is also totally normal.
Good for you for nursing this long! Hope something here helps. Happy New Year!