Short period, followed by implantation spotting?

[Natvana]

Hey! So my hubby and I are not actively ttc since we have 4 kids. However, we bd on the 15th and I'm not sure when I ovulated. I had what I thought was the start of my period on the 22nd. It started out spotting, then a light flow on and off for about 1.5 days, then spotting for another 1.5 days. My period is usually 4 days. Then yesterday, twice when I wiped, I got a little pinkish discharge. It was like pink snot (sorry TMI). I've been having symptoms so I took a test but came out bfn. Could I be pregnant even after bleeding?