My boyfriend and I had -protected- sex on the 11th of May. I'm due for my period anytime in between tomorrow, the 23rd, and wednesday the 28th. (I have irregular periods, 27-32).

During the day we had sex, it was on the 15th day of my cycle, which i am still continuing right now. This lands me right in the middle of my fertile time.

We used both a male condom and VCF (spermicide). (They were both used correctly.) I am not on the pill because of other medications I already have to take. I'd really say I felt very safe.

I've never had sex with him in any other cycle other than the one I'm in.

However, ever since sunday the 18th, (4 days), I've been having sore breasts that are unusually sore compared to my usual soreness. I've actually been noticing that they're considerably bigger. I've asked people and they've said the same. Now, to my utter dismay, I've noticed that my nipples look darker. Does it make sense for this to start approx a full week before my period??
This sounds very much like a pregnancy symptom, I know. However, could it possibly start only 1 WEEK after the possible time of conception? It would only make it a week in between sex and soreness, so could that still be a pregnancy symptom?

Still, I have been getting cramps. Would this indicate that I couldn't possibly be pregnant? I've even noticed that theyre on one side, like they normally are during a cycle.

I've also noticed that my regular "wet" days ended just a little bit ago. (Maybe yesterday was my first dry one.) This would mean that my cycle seems to be continuing on its regular routine, just 8-ish days behind. This makes me think that it could just be mother nature playing tricks on me, because I know that often after you become sexually active it messes up your cycle. Which could explain the soreness because there would be a bigger amount of time for them to become sore.

So... Is it too soon for these symptoms?
Could these mean I'm pregnant?
Does the last paragraph sound like a good assumption?

Numbers:
On 27th day of cycle;
Tomorrow = first pos period, Wednesday = last
Sex on the 11th, or 15th day of cycle
Sore breasts on the 18th, or 23rd day of cycle.
Days since possible pregnancy: 11

I would EXTREMELY appreciate if someone could get back to me.
I'm going insane.