Advice???

I'm so confused right now. I haven't had a period this month, but I did have some dark colored light bleeding for about 3 days. Could that of been implantation bleeding?? I had slight cramping after the bleeding. I've been very tired all the time, and constipated. Could I be pregnant?? I haven't taken a test yet, just want to make sure this all isn't in my head. I've been trying to conceive for about a year now. Any advice??