My whole body feels like im pregnant, but i am so unsure

I got married in April, 2011. Since then we are ttc. I had my last period on the 3rd of Feb, 2012. (not much heavy, just a 3-5 day cycle, bleeding till three days and little on the fourth and fifth day). I had ovulation bleeding on day 14 of my cycle (i.e., Feb 16) (P.S: i had never had ovulation bleeding before) which lasted 1.5 days (slight bleeding). Me and my husband had sex 1day before i ovulated and on the day of ovulation, and a day after ovulation (Not afterwards up till now have we had sex). (i.e., Feb 14,16 and 17). On Feb 22, i felt i had a metallic taste in my mouth which lasted a day only. On Feb 23 i started feeling a burning in my stomach which has never happened to me even before a Period. I had backache just for a while. I had my period expected on the 1st of March, 2012 (since, Feb=29days). I didnot have my period, instead on 4th of March, i started spotting some brown/orange-pink discharge (small 2-3 spots only when i wiped) i didnt bleed, just slight spotting off and on the whole day, and 1 spot the other day(a bit red). Thats about it. I felt like i was getting period like cramps the whole while till my periods. but NO periods.

is this Implantation Spotting?

Secondly, i feel like im discharging, i have some slight pain/acidity in my abdomen. i feel tired and sleepy all the time (even after ovulation i felt tired and sleepy). i get headaches for half n hour or less off and on. when i walk alot i get a pain like period cramps and it goes away when i take some rest.

i had done a pregnancy home test before my period date was due and it came out negative. i took a HCG on the day i spotted (March 4) but it came out negative. I had high temperature the whole day. Throughout i had high temp but not as high as compared to the one i had the day i spotted.

I havent had my period as per yet. 

Im confused. My whole body feels like im pregnant, but i am so unsure.

Regards,

Maria*