How can my boyfriend and I practice safe sex when the condom will not stay on his small penis?

My boyfriend and I are devoted to each other. We’re also devoted to having safe sex and avoiding pregnancy. I’m on the pill and we use condoms, but the condoms don’t always work. Here’s why:

1. His penis is small. I’m talking very small.
2. He has trouble keeping an erection, so his penis is even smaller sometimes during sex. This is the part that really troubles me. He is erect when we begin but not always fully erect after that. This, of course, causes the penis to become loose.

I’ve been searching the internet for small condoms and I’ve found a few things. I really don’t want to purchase them from embarrassingly named websites, though. I have roommates who check the mail. And he lives with other people, too.

We’ve had a recent scare when the condom sort of flopped off because of these problems. I’m very worried. I don’t even know which of the two issues is more to blame. My boyfriend has very little sexual experience, so he’s pretty stumped, too. This is wearing on us.

Any suggestions, advice, or information would be so helpful.