that's horrible your gynecologist told you that you lost the baby bc of breastfeeding, that sounds like an old wive's tale. generally pregnancy's don't develop bc of a chromosomal problem i think. it is hard to breastfeed and be pregnant bc both kids are depleting you of nutrients, and it will make it much harder for you to be well rested and nourished, but you can take extra nutrients. i personally wouldn't recommend getting pregnant again so fast bc resting first does help YOU bc you'll be that much more tired with another pregnancy.
i have terrible sleep problems with my little one too but i did have luck with my first son so i'll just share that story with you.
he co-slept and breastfed about every two hours to sleep until he was 17 months. then i watched an episode of the baby whisperer on tv and it gave me hope and courage to try sleep training and stop breastfeeding at once.
my son had never liked his crib so i took the matress out and put it next to our bed on teh floor (i also put our matress on the floor). instead of breastfeeding him, i gave him a bottle before bed and then hugged and kissed him and told him "you are going to sleep now, i love you, i'm here with you and you are safe." i put him down in the bed and he cried. every time he cried i picked him up and repeated my mantra "i love you, you are safe, i'm with you, you are just going to sleep now, good night" and put him down again. i picked him up, comforted him, and put him down in the bed for at least 45 minutes maybe an hour, before he finally fell asleep on his own and stayed asleep.
there was a lot of crying but he was never alone and never left to cry. i always comforted him and then put him down in the bed.
it was miraculous. that night for the first time he only woke up once the whole night. when he woke up i did the same routine, pick up, mantra, put down. no shaking or rocking or nursing. this time it took 15 minutes and he fell asleep til morning!
within a couple of days he was sleeping through the night.
what the baby whisperer said was that if you are going to try sleep training you must be 100 percent committed or it is cruel. you must see it through. you can't let him go through that nad then breastfeed him bc he will be getting mixed messages.
i hope that might help.
good luck and please take care of yourself, rest when you can, take vitamins, eat lots of veggies and fruit and organic eggs and lentils and almonds....and do consider giving yourself a few months to rest before trying to get pregnant again, for your sake, to be well rested and spend some time with your son.