I did not follow up on my feb depo shot and it's may I have had 4 periods since then a little nausea here and there and my breast are a little sore is it possible to get pregnant so soon after the depo?

It normally takes several months and even years for the effects of the shot to wear off.
While it is not impossible it's improbable,
The only way to know for sure is an HPT with morning urine.