Potential first signs of balding, aged 21

[DuckingAngels]

Hi guys. I just joined this forum yesterday so I could post this. I feel that my situation is particularly complex.

My hair was fairly perfect up until six months ago. I then went through a stressful period, including the break up of a long term girlfriend, frequent exams, and my diet and sleep patterns became unhealthy. I also began to swim every day (without any special kind of chlorine removing shampoo).

About three months ago, after a few weeks of vaguely being aware of the fact that my hair was suddenly much harder to style, I eventually noticed that my hair looked a lot less healthy and thick. The sides seemed to have receded a small amount (slightly more on the left hand side). The bits just left and right of the front hair have also slightly thinned out. It's hard to say, as my crown does feel slightly thin, but I'm not actually sure much has changed there in the last six months.

In the last month and a half or so, my diet has improved, my stress has dropped a lot, and I am generally much happier. I have also been using the alpecin shampoo, which seems to have helped thicken up my hair a bit. I also have stopped swimming. My hair has slightly improved - mainly in terms of thickness- in this period.

Currently my hair is still in a pretty good state. I don't think that anyone would notice anything yet. But I have a real issue with trying to correctly explain the reason for this hairloss. My dad, my uncle and their dad all went bald around 27-32, whereas my mum's father had very gradually receding hair from about 30. He still had decent coverage at 40. So whilst I am probably genetically destined to go bald, it doesn't seem likely that it would begin this early (I'm 21). Also, lots of other reasons that supposedly cause hair issues- stress, diet, chlorine etc.. have all been present in my life.

I ordered some Rogaine foam, but I am now quite unsure whether or not to use it. In some sense, If i start now and maintain this level of hair (wouldn't even really need to regrow any area) then I would be very happy. Of course this is a big financial commitment. It is just a hard decision to make, because I could potentially be facing only a mature hairline, and not the onset of MPB. Or it could be that stress/diet etc caused the loss. I am worried that if I use Rogaine for three years hypothetically, I will be unable to tell whether it is 'working', or indeed, even necessary, because it could simply be that I wasn't going bald anyway. Then I'd face a difficult decision between staying on it and potentially paying for nothing, or coming off it, and suddenly shedding loads as it was maintaining a lot of hair.

It's a difficult decision, starting nice and early, with a risk of jumping the gun.
I really don't want to leave it, and then lose hair that I can never regain, and yet I don't want to be taking this rogaine stuff for years, without even knowing if it was necessary.

Does anyone have any advice? The thing that seems most indicative of MPB is the bits just to the side of the front thinning out. I don't think that is just a mature hairline, but then I really have no knowledge. Does it sound like MPB?

Sorry for the long post.