maybe see a different doctor about it.
my sister had a heart murmur when she was pregnant, she was only 17 when she gave birth for the first time. im not sure if it was from the heart murmur, being so young or having a long labour but she had a really bad time and almost didnt survive and needed a blood transfusion.
but honestly im not sure what the reasons were for it being complicated for her. so just ask a different doctor about it. hope it all goes well 4 you! best wishes