jilll - it looks to me like that first A time is definitely too short. A 45 min nap often indicates undertired, and with an A time of only 45 min, I'm certain she's undertired. 45 min is what a newborn would typically be doing. At 5 mos, 2 - 2.25 hrs is more typical. It looks like you're trying to at least feed on a 4 hr EASY, so that works best with 2 hrs of A time. Is it possible that what you're seeing as tired cues are really "I'm bored" cues? At 5 mos, your lo is much more aware of and interested in the world around her, and may just want a change of scenery.
I would definitely work on extending that A time - start with the first one of the day and just add 10 - 15 min every 3 days. You want to keep that extra time really low key - even think of it as an extended winddown time. Then, if her nap is short, you'll want to keep the next A time a bit short as well (since she won't be as well rested to handle a longer A time). You want to be moving towards 2ish hrs of A time, keeping in mind that the first A time of the day may remain a bit shorter. Does that make sense?
hth
michelle