is this your first, i take it?
it is amazing how your body will adapt to accomodate the growing baby...rest assured, that you will grow the size of baby you can carry and birth !!
i think it is really important to have a positive, where possible, mindset...and not think in terms of , well, i am short, so i will have a bad time , or this will go wrong...best to trust in your body and believe that you can do this !
you will become uncomfortable as you reach the end of the pregnancy, as your organs do get squashed , but that does lessen a bit as the baby starts to engage..i think that is true whatever height you are ! and , once the baby i s here, you do tend to forget that you were breathless and had heartburn!
revel in the fact your body is growing, protecting and nourishing another person !
i always recommend that you should read about positive birth stories
Ina May Gaskin's Spiritual midwifery and Ina Mya;s Guide to childbirth are both excellent, as is pretty much anything by Sheila Kitzinger....
HTH x