According to Webster, bi can mean every two months or twice a month And semi can also lead to misunderstanding Perhaps it is better to state what you mean by simply stating either "every two months" or "twice each month "
a periodical that is published bimonthly occurring every two months; "bimonthly visits" every two months; "the bill was payable bimonthly
Occurring, done, or coming, once in two months; as, bimonthly visits; bimonthly publications
bi·month·ly in BRIT, also use bi-monthly A bimonthly event or publication happens or appears every two months. bimonthly newsletters. appearing or happening every two months or twice each month monthly, quarterly quarterly
a periodical that is published bimonthly occurring every two months; "bimonthly visits"