Hi there!
1.75 - 2 hours of awake time sounds right to me for her age, so I wouldn't push her for more right now. When I was extending my DS's awake times, I would do a little bit (5-15 minutes depending on how well he handled it) to each awake time, unless he had a shorter than usual nap. It usually took him three-five days to sort himself out and be ok with the longer times, but once he did it was much better.
My DS was horrible about naps and NWs too. Just keep helping Fiona get back to sleep during the nite (shush/pat, pu/pd) and eventually she will figure it out. It was at about 6 months when Finn finally got the knack of making it thru the nite on his own. He also had/has some awake times that are much shorter than the others... I have no idea why. His schedule doesn't seem any different, but he just crashes much sooner than usual. I just roll with it - every day is different with him!
Hang in there with your little DD! It WILL GET BETTER!!
Good luck, A