okay so here's what's going down...
my last period was the 4th of September, but on the 14th/15th of September me and my boyfriend didn't use any protection and he ejaculated into me, by accident but we really should have been using protection.. anyway I ovulated on the 17th,18th sep.
then on the 25th of sep I had this light spotting/bleeding thing, and I usually have heavy periods but this time I only had to wear a panty liner. Would this have been implantation bleeding? Since then I've had a lot of different symptoms, sore boobs that are bigger ( my bra was even tight), feeling sick at random times of the day, light headedness, dizziness, cramps in my abdomen, veins in my boobs are more obvious, VERY bloated.. me and my boyfriend arnt trying to conceive but it would be very nicee.. I just wondered if I could be pregnant.
thanks xxx

Implantation bleeding is very very rare. A fertilized egg is microscopic! Hardly enough to cause noticeable bleeding when attaching to the uterus.

That being said... with the timeline you have given, it is very very possible you could be pregnant.

But pregnancy is a waiting game. When are you due for your period? I would wait and see if it comes, keep in mind though, you just merely thinking you could be pregnant could cause your period to be late.

I would wait until you are due for your period, see if it comes, if it doesn't take a HPT.