Is it possible to miscarry before i have implantation? it definitely was not period. but i just have that feeling that i conceived.

Not exactly...: If you haven't implanted, you're not "carrying". If you're not "carrying", you can't "miscarry". There are likely many fertilized eggs that don't successfully implant. If they don't implant at all, there are no positive pregnancy tests. If embryos implant and then die, there may be transient positive pregnancy tests. That may be the case when an early positive test turns negative a few days later.