Im Pregeant or nto ???????????

hi my name kayleigh im 17 nearlly 18 i have babby girl allread she 8 mouths old and ? i have boyfriend hows had the snip done and he had it for 3 year now of coz we had but i have my normal period which 7 days period and last week tuseday i come on my period but i come off gan and i have not been ack on yet and im dizzy sickey and little bit tendernss ???????? does that mean i could be preant plzzzz i need to know if this right i am his snip not work