Implantation bleeding?

I had my last period on 11th of February & ovulated on the 19th. 
​I took a pregnancy test four days ago & it was negative. But this morning I was having very light bright red spotting. & have no period like symptoms & since my last period I have went up a cup size. 
​I'm so confused so I'm going to call my doctors on Monday. 
​ 
​Any insight would help would love to hear some input.