oh, mama, i hear your disappointment and desparation. i couldn't not send you hugs and let you know how strong you have been carrying those two babes! 
i can totally relate to how you might be feeling in the wake of baby a still being in the breech position. i know the timing is getting quite close....but your baby certainly can flip in the next two weeks! we will all be sending flip, baby, flip vibes to your babe. i second the pp who mentioned how many physical excercises you can do to encourage baby shifting, though i imagine it is slightly different with two in the oven.
i would say, talk that baby down. talk him/her into the ideal position. constantly envision the baby flipping inside you. have a mental image of it that you can meditate on. instead of letting yourself be annoyed when you feel the hiccups in the same place, turn that into a moment where you imagine the baby moving into ideal placement....use the hiccups to help you mentally place where you want babe to be. ask baby b to make room for his/her brother/sis. i would send as much positive turning light and energy to your womb as possible, and really try to wait a minute on the feelings of disappointment... there is still time!!
when it comes to feeling so disappointed about the possibility of a c-section, when it comes to that for sure, i offer you my virtual shoulder to cry it out. own your feelings. i can totally understand how disappointing that reality is, i would be right there with you. birthing is not just about a healthy baby (babies) in the end, it is also about a healthy mama in the end. should a c-section be your reality, and i know we are all rooting for you and baby a so that it is not, let yourself grieve losing your vaginal birth experience this time. get it out as much as you can. don't let any guilt creep in... of course you want what is best for your babies. wanting what is best for their mama is also wanting what is best for them. how daunting it must feel to think of a c section and then coming home to care for two helpless babies. i hear you, and more hugs your way. the best way i can see coming to terms with that, should it be the case, is letting all of your disappointment and anger, sadness, etc, about the situation OUT. you are in no way a bad parent for envisioning a different birth for yourself. birth is not entirely about babies.
(as a light at the end of the tunnel, i do know a mama on these boards who's first babes were c-sectioned twins, and she went on to have i think like 8 more kiddos, all at home, mostly uc. one c-section, again- only if it ends up that route, does not mean you will never get the birth you envision!)
much love your way!
turn, baby a, turn! 
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