Can Letrox affect the effects of Vines birth control pills?

Good morning, for a month I take drugs for hypothyroidism ie LETROX 1 tablet, currently I got bleeding from withdrawal vines but the "period" really lasted from 1 day. Where with vines tablets it lasted about 3. I take vines tablets for about 2years. Is that normal? Can these drugs affect each other? I kind of told both doctors about the drugs I was taking, but now I'm a little worried.