You do not say why you do not want to use THe pill. However getting pregnant while using a condom is not that uncommon, since they can break quite easily. This happened to me when I was first having sex with my now husband. I ended up using the morning after pill
.Also the male needs to withdraw straight away after cllmax, as sperm is more likely to leak out when the penis is limp and the condom may slip off(sure you would have thought of this).
A good idea might be to use the rythem method along with using a condom.........having sex during infertile days(not ideal when a relationship is in its early stages because being spontaneous is part of the fun)