Shouldn't have another baby, but I want to

My husband and I have a 3 year old son and an almost 2 year old daughter. We have talked about it many times and due to the fact that we live on one income since I am a SAHM we think we should not have any more kids for at least 5 more years. Yet every month I catch myself REALLY hoping I don't get my period. I know we shouldn't have any more kids any time soon. We would struggle bad with a new baby and that isn't fair to the two babies we already have. It makes me feel guilty for being so baby hungry!