**ADDED: You don't have to ask them for sizes, all sizes should be out on the shelf. No conversation needs to be had, and your husband doesn't need to be the one to buy them. It wouldn't hurt to try. Also, you need a Dr. to prescribe the birth control pill, so you would have to worry about not only the cost of the pills but also the appointment cost. I'd say go look online for condom sizes, http://www.trojancondoms.com/Product/ProductListVert.aspx Or even contact Trojan over the phone. They would be able to help you. and I'm sure you can even order online. You would not have to worry about in-person exchanges...**
(Thea and Dana, she MAY be saying that her husband may have the opposite problem with condom size............)
Condoms do have different sizes which can be found at any drug store.
I have never been regular either, but natural planning is still an option for you. You don't ovulate every week. Before my husband got a vasectomy (another option for you. It does cost money, but a small fraction of what a baby costs), I just used the 3 weeks after I ovulated, as "in the clear" times. Any other time like that is a guessing game.
Another option is a diaphragm for you.
Birth control pills (and any medicine) effect people differently, so there is no guarantee how you will feel, and what side effects you may have. I'm just personally not a fan of them in general.