Sperm or fertile cm??

So my bc is a marine and we have been trying for a while!! I have irregular period so Know my cycle days. My period was September 12th last 5 days. Me and fiancé did the deed yesterday and today when using the rest room I wiped and long stretchy clear discharge so I checked with my fingers and it stretched far. I’m not sure if it means I’m fertile or his sperm?? Hopefully this will be the month ❤️🤞🏼