not sure when i am ovulating?

hi me and my husband are very new to making baby, i need to no if there is a chance i cud be pregnant? normally my period is due the 20th of every month but last month a come on on the 18th for only a day then stoped still had period pains then properly come on on the 25th, we last had sex about 9th-13th everyday, i have not cum on my period yet could i be pregnant?????????????

thanks sam xxx