A receding hairline, caught early, could be just a developing mature hairline. Most men's hairlines move back a bit in their 20s or 30s. No treatment for this.
Check the back of your head with two mirrors for thinning at the crown- that's a dead giveaway. However that doesn't always occur, so it's only an indicator that you do have male pattern baldness, not a way to prove you don't.
Also check the hair behind your hairline- if it's thinning, that's an indicator you will recede farther.
Also, if the hair that comes out in the shower/comb/on your hands is often shorter, thinner, and lighter in colour than the rest of your hair, this is a sign of minataurization. This only occurs with male pattern baldness.
Just shedding what seems to be a lot of hair is not an indicator of male pattern baldness.
If you go to a doctor, you need to get refered to a dermatologist. A general practitioner is pretty useless, they don't seem to know much more than the average person about hair loss- if you catch it early they probably won't be able to tell. A dermatologist has a lot more experience and can do something called a hair pull test.
Good Luck.
And, most likely,
WELCOME TO HELL!!!!!!!!