Help !! Depo/ pregnancy

I’ve recently got my depo shot 3 weeks ago I’ve been on it for about a year. My boyfriend had cum in me on Sunday May 17 and Tuesday May 19 of this month saying he wanted to have another kid. I’ve been experiencing cramping and light/mild red brownish spotting ( i never bleed while I’m in depo) could I be pregnant or to soon to tell?? btw I took a test but negative