Unfortunately, it doesn't matter if your boyfriend ejaculated in you or not if he had his penis inside your vagina. The pull out method does not prevent pregnancy as the penis emits small amounts of sperm that is enough to get you pregnant. So use a condom or get on the pill! The thing with conception though is timing too. There is no safe time, you can get pregnant any time during your cycle, BUT . . . there are MORE fertile times than others. This is how a typical cycle works . . . day one of your period is cycle day one. You count from there. Starting around day 9, you enter the more fertile time. It lasts until about day 15 with ovulation usually occurring midway through your cycle on about day 14 to 15 of the cycle. This is based on the average woman's cycle so adjust if yours is longer or shorter. Women usually don't immediately get pregnancy symptoms so they aren't a good way to tell you anything about being pregnant (often misleading too because pms symptoms and hormones cause all the same things so it's hard to say what is going on as it is all so subtle). Women do have spotting and if it is brownish in color, that's often old blood.
So, that's a lot of words that all add up to I don't know for sure. LOL I actually doubt it though and don't think you are pregnant from what you've written. But the best way to know is to go ahead and buy a cheapy pregnancy test and take it. Follow the directions and only read it during the time frame they say as leaving it sit can cause an evaporation line that a lot of girls then think means pregnant and it doesn't. So, follow directions with that. Try not to worry, I don't think you are pregnant but take a test to confirm that. Use protection from now on! good luck