How do I know what condom size to buy?

In my shopping and looking for condoms, I NEVER come across a formal size chart. I have been told that I was "endowed" and that I need to look toward larger sized models, but all I ever see is "snug fit," "large," and "extra large," etc. How big is big? It would be most helpful if I knew what I was buying before I actually bought it. Do you know of the sizes of some popular condoms, or of a size chart resource?


Is Mirena safe for those who have yet to give birth?

I have recently been advised that my on-going migraines might be caused and/or increased by the use of contraceptives containing estrogen. To that end, I have been recommended to switch to a progesterone-only form of birth control. Which, in turn, basically means I get to choose between Implanon and Mirena (I really can't stand needles, so Depo is out for me!). I am only 23 years old, and have not yet started a family. I do want to have children someday, and am very enticed by the idea of Mirena lasting to the point when I might want to begin trying to get pregnant. However, all of the advertisements for Mirena state that ideal candidates have already had children.

Is Mirena still safe for use in women who have not yet given birth? If so are there any additional side effects to consider in this instance?


What are the common reasons for condom failure?

I live in Prague, Czech Republic — Europe. Before asking any question, I should tell you that I really appreciate your service. As for my question, I would like to ask you about the most common reasons for condom failure as a contraceptive method. I suppose that the most frequent one is condom breakage. But what are the others? I am especially concerned about pregnancy risk implied by the accidental transfer of sperm in pre-cum to condom by fingers while putting it on.