Congratulation on new baby!
whatever the gap I find the first 6 months the hardest, it does get easier afterwards.
I love 2 year gaps, they were perfect for me!
we had 2 years between DS1 and DS2 (both in July), between DS3 and DS4 (both in December), then between DS5 and Dd (May and April)
the gap of 17 months between DS2 and DS3 was too quick for me, and 3.5 years between DS4 and 5 were too long, but couldn't help it as we lost a baby in between.
I don't mind the longer gap now, but it does remind me of the loss sometimes.
it is hard though when they are both so needy, I do sympathize!
the one thing I can advice you to do that saved my sanity is Priscilla Dunstan and her "baby language".
I can't do a link, I'm rubbish, but just type in "Priscilla Dunstan on Oprah" and watch, learn, be amazed and sob with relief when you realize that by distinguishing between the sounds your DD2 makes you can cater to her needs. making everyone so much happier!!
make notes and use the info she gives and I promise you that you'll feel in control, that you'll know what you are doing and it will transform your life!!
as soon as you learn the clues your baby gives you, you can help her sleep better too, this will give you a chance to rest and/or pay more attention to DD1.
I wish I had this knowledge she is sharing when my boys were newborns, it makes me cross how we all suffered from me not knowing what they actually needed!
but thankfully my baby girl benefited, so I guess better late than never.
watch it now, then get back to me. I'm happy to chat more.