Hey Alisha, I think we are in a very similar boat fertility wise. I have been thinking about this A LOT because I am definitely not ready for sterilization - I'm like 95% sure I want a second, I just would rather not have one right now! Lillian is a lot of work and I don't know how I would be able to hand two really young kids + CF.
Anyway, my thoughts have been, we had cervical mucus issues before, and I think those are probably still present, so I doubt we'd get pregnant more easily. However, I know many women in the infertility world who needed IVF to conceive their first child and then got pregnant with their second very easily...so I'd rather not take the chance. I went on the minipill at 6 weeks postpartum, but it completely killed my sex drive, so I decided I'd rather not do a hormonal birth control. We hate condoms and spermicide. I'm breastfeeding so we can't do natural family planning. So that pretty much leaves the IUD. (Right now don't have to worry about anything because I found out I am still recovering, so abstinence it is).
I'd actually love to get thoughts on the IUD. There's Mirena and Paragaurd. I've heard Mirena is "better" because it releases a hormone that stops your periods (but I guess it doesn't have the side effects of the pill). Paraguard is just a copper coil that makes the environment unhospitable for sperm, so you don't stop having your period and they usually become worse - not so fun. HOWEVER, my OB said Mirena also thickens your cervical mucus. I'm scared to make my cervical mucus even MORE thick. What if I create some sort of plug that affects my fertility? I asked my OB this question and she thought it wasn't a worry because things should just go back to normal when the IUD is removed. But, she's no CF expert by any means. Anyone have any thoughts on this?
Anyway, Alisha, have you looked into Paraguard? I wouldn't think it would have the same weight issues. It is what I am leaning towards this based on the above paragraph.
Oh, and are you nursing? If not, you might be able to try natural family planning/charting - not as affective as the other methods, but it's an option. If I wasn't nursing and my periods were regular, I'd probably be going that way because my periods were really regular before I got pregnant and I don't mind taking my temperature every morning. I figure doing that + my thickened CM would be good birth control <img src="i/expressions/face-icon-small-wink.gif" border="0"> But, with nursing, I never know when my period might show up, so it doesn't work right now.