2 weeks late help!!!! :(

Heyy ladies! Ok so I was supposed to get AF on march,9th but have to or any signs of receiving it. I've been tierd,mood peeing alot and some slight back pain and abdominal cramps. Nothing like a periode cramp! I've taken 4 hpt witch either I'm crazy or have faint positives on them all. Want for a blood test yesterday they told me it was negative and my hcg level was only 2 I'm so confused and just want to know what's going on!!! Any advice would be greay! Anyone else ever experience somthing like this? Ended up being pregnant? Do you guys are any thing or am I going crazy??