Worried...

My fiancee and are very worried that she could be pregnant. We have not had sex yet...but there are circumstances that may have, however unlikely, lead to [url="http://www.healthboards.com/wbmds.php?w=pregnancy"]pregnancy[/url]. At one point, I had put a condom on, with spermicidal lubricant, and barely entered her...basically on the outside of her...and there was quite a bit of precum in the condom...but I was not more than probably an inch inside her, and the condom did not break or slip or anything. The other circumstance is that we were taking a shower together, and I was hard the whole time, but I am unsure if I precame. However, at one point my penis had made contact with her vagina...but it was not near the hole...it was at the very top, above the clitoris...if it had even made contact with the vagina at all. She has missed her period...but we got a pregnancy test and it came up negative. We're going to take another one soon...but we are scared that she may have gotten pregnant from one of those incidents. Help would be appreciated. Thanks