Birth control?!?!

I went to the doctor yesterday to discuss my super heavy irregular period. She asked me how long do I have before I decide to have kids and I said "a few years (3 years) at maxuim." She said that they don't want to put me on anything with estrogen and that I only had 3 options. The Deppo shot (lasts 3 months), Mirena (iud)(lasts 5 years), or a stick like thing that they implant into my arm (last 3 years). I'm not going to even consider the Deppo shot because there's a medicine that I take that has me gaining weight like crazy. Mirena is recommended for people who have already had a child. Why is she even trying to have me consider it? I don't have a child at all plus I'm 18. I'm not going to have anything placed inside my uterus that runs the risk of going through my uterine wall. I have a desire to have kids! My fiancee is not happy about these options!!!!!

What's the point of even recommending birth control to someone who plans to have kids between now and the next 3 years?!?! Are there any other options to lighten my period and regulate it besides birth control?