HELP ME PLEASE IM SO SCARED

Am I pregnant? Okay so 8 weeks ago I gave this boy head (sorry) and then I'm not sure if I got some on my hand or not but defiantly not visibly. Then about 40 minutes later I think, I went to the loo but I forgot to wash my hands!

thought nothing about it and went to sleep. Then 6 days later I noticed very light spotting and thought it was my period so I put a tampon in and then I got home and removed the tampon and there was nothing on it?

The next day this spotting got a tiny bit heavier until my period started properly the day after that, this period only lasted properly for 5 days with properly heavy bleeding. Then the period after that only lasted 5 days aswell but was lighter and started off brown.

I know that this is probably near to impossible but is there anyway that when I went to the loo I got sperm on my vagina and it somehow got me pregnant? Could the spotting have been implantation bleeding?

Sorry if this is to much detail but I just need reassurance as I only 16 and never had sex before but I've read that people can still have their periods when they are pregnant