I have my IUD planted on me and every month I still worried that I might not get period n get pregnant :(

Hi. Have anyone here have same problem with me? My son is 2 years old and to be honest a month after I got married, I got pregnant. It wasnt hard for me and my husband to get concieved. And since that time I always paranoid wether I get my period or not in each and every month eventough I got my IUD planted in me. It also frustrated me at the same time. Me and my husband both are sexually active sometimes he also put a condom on but some other time he wont. Me and my husband want to have sex freely (without condom) but I dont want to get worried about getting pregnant :(