Possibly pregnant on implanon? Confused

hello. i am so confused right now and desperate for some kind of advice.

i currently have 4 children, and i had the implanon inserted about 18months ago.
my periods have been regular whilst i have been on it. up until last month, i got all the period pains, and all signs of coming on, yet it never started. i didn't think much of it at first, until the first of this month came about. then that's when i thought, this isn't normal.
since then, i have been having pregnancy symptoms. on top of that, i just FEEL pregnant! i am convinced i am! i knew i was pregnant with my 2 youngest because i just felt pregnant.
i have had 2 HPT and a u/s taken at doctors, which all came back neg. but i still FEEL pregnant, and still have preg symptoms??
i am being patient, and waiting to see if my period comes this month or not. it is killing me waiting. i have ordered some preg tests online and am currently (impatiently) waiting for their arrival!

my symptoms have been:
nausea, vomited once, very hungry and eating alot more (unusual as i am anorexic), i have been very, very emotional, some days i have been so moody to the point nobody could speak to me without me creating an argument out of what they said. then other days i have been so full of beans it was odd lol. not saying i'm miserable, but i have been over the top happy lol. my legs have been achy, my upper back has been achy, my hips have been awful some days. my stomach keeps getting achy also.

now i know the implanon can create pregnancy like symptoms. i understand that. but this is my 2nd implant. the first one i had in for the full three years. i never had any problems what so ever with it.
if anything, it had been good for my periods, as it made me regular. obviously, with me being anorexic, sometimes (not often) my periods play up. but they never have on the implant.
also, if i was going to get any pregnant like symptoms, surely they would have started at the start of the implant, rather than a year and a half later.

just to add, my anorexia is quite stable (i am very small - and small framed), so it doesn't affect my periods much at all. especially at the minute since my weight has increased lately (ANOTHER SIGN!)

do you think it's possible that i am, and just tested too early - or even have false-positives?

any input would be greatly appreciated

thanx