Am I getting excited over nothing?

Here is my story...

I was on the depo for 3 months but havent got a shot since May 10. The OBGYN said it may last from 12-18 months on my system (I was pissed she told me that AFTER the first shot). So here we are... 10 months later and my period (which started after my last Depo shot in October) is officially 2-days late. When I mentioned to my husband, he thought maybe because February only has 28 days, I miss calculated. Well when I calculated here, it says I am actually 9 days late! Yikes. We definitely want another baby but I dont want to get my hopes up for nothing. My breast feel like they are about to explode and I am SUPER bloated (and only had a couple of strawberries). The only sign missing is the drowsiness. I am not sleepy like I was with my first pregnancy. Could my cycle just be changing or what? I am freaking OUT! I took a home pregnancy test last night and it was negative. Of course I was super dissapointed...