How can i distract myself from wanting to have a child?

I'm only 21 and have only been with my boyfriend for a year and a bit, now is not the time for me to go baby crazy and I know that. However it is a little harder than it sounds for me. I had a miscarriage at 18 due to some rather unpleasant events and ever since then have had a fear of never carrying to term. It's very important to me to be a mother and though I know it is illogical for me to be longing for pregnancy I can't seem to help it. I don't mention it to my boyfriend as I don't want to scare him and I already know full well he would like very much for us to have children, just not now. Some months I don't think about it very much but the second my period is late I go through this fit of emotions until it starts, hoping silently to myself that I'm pregnant but denying to everyone around me that it's even a possibility, and when I do start or dont and end up taking a negative pregnancy test I feel disappointed, but I feel guilty because I shouldn't want to be pregnant... and this happens nearly every month as my cycle is not normal, if I'm not late im early.