Help me understand!

Okay so I got a positive lh surge test on October 4th.. so I assume i ovulated that day or the next day. On the 5th the lh surge test was negative. I looked back through text messages between my mom and I and I was talking about how I was cramping from my period on September 21. I dont usually keep up with when I start and stop my periods. My periods are only 3-4 days max after having my son 2 yrs ago! My question is would I have ovulated that soon after stopping my period? Im not sure what day of my period I was on when I text her that. Attached below is my positive LH surge test on October 4th.