I don't think its capability of life is much of an argument philosophically. A 2 year old wouldn't make it without close attention of its parents/guardian.

While it's true that a two year old cannot survive without the care of someone else, it's not for remotely the same reason that an embryo cannot survive without its mother. Conflating the two really doesn't make sense.

A two year old cannot survive on its own as a matter of skill and ability. But it is not reliant on its mother for that survival; any person can take care of it. As long as someone helps the two year old obtain food, water, and shelter, it will survive.

None of those things is true of an embryo. An embryo is dependent upon its mother for survival as a matter of its physical makeup. It does not possess its own blood supply or organs or anything we could even call a body (depending on the point in gestation). It cannot be removed from the mother without dying, even if someone identical to the mother tried to take care of it in the same way.

my point is this: if it has the capacity/potential to grow into a healthy human being, I'm uncomfortable with the idea of preventing it from reaching that potential. Any one of us could've been aborted.

You're certainly allowed your own philosophical belief on that, but I simply don't agree. Sure, any of us could have been aborted, but I don't see why that should matter. If you define "us" from the point of conception, then any of us could have failed to implant and died then, or been miscarried, or had something affect our development during gestation and become entirely different people. None of that really impacts anything.

I don't find "potential" particularly convincing either. Even if we say that an embryo is a potential human being, its mother is still an actual human being. To give the embryo a right to develop is to trample upon the mother's rights to bodily autonomy (and I realize that you said you support abortion as a necessary evil; I'm just talking abstractly here). I've yet to see a convincing reason that we should accept that.