Implanon, supposed UTI and mixed pregnancy test results. HELP!

I have had implanon in for almost two years and my bmi is 35.

20/07/09- had intercourse
01/08/09- I got a very faint positive reading on my regular hpt so I went to the doctors to be told I have a UTI and got sent home with antibiotics and a negative second pee test
04/08/09- paranoia due so symptoms that I'll list below so took another test and that one showed a faint positive as well.

I have cramps, lower back and hip pain, irregular appetite (not wanting to eat most the time then on occasion an urge to eat but feel sick because I ate even in the first mouthfull even if i feel sick because i need to eat), irregular sleep but constantly exhausted, first blood nose since last pregnancy, weird spotting (i don't usually have any bleeding) and a few other things that are too personal.

I do not have any symptoms of a UTI as I do not even feel the need to "go" anymore often than usuall am not itchy "down there" and havn't any pain during, before or after urination and I have had a UTI before and it felt like I was pissing razor blades sooo painfull but this time (if it really is) there is absolutely nothing and my flow is strong and regular.

Why would I get mixed pregnancy results cos if there was blood or protine in the urine should it not have came up "false positive" at the doctors as well?

My tests were not done in the morning so that shoud not influence one test over another.

I would be ~15 days from conception today does anyone have any ideas?