I do think she's a little too young for just 1 nap. During the transition period, its not uncommon for them to go from 2-1-2-1 naps. I would definitely keep offering the morning nap (especially if she's waking up so early in the morning). If you find that 45 mins is refreshing enough for the rest of the day, then cut it down to 30mins. If she's still resisteing the afternoon nap, then I would push that morning nap until you get to midday. But you do have to do it in increments to avoid the overtired state. Add 15-20mins to her A time every 3-4 days until she is taking her nap at 12pm. During the transition, you will probably have to bring the bedtime forward as well. At the moment 7hrs A time is waaay too much. My lo can only just do that now (if I push her) and she is 2.
Could you post your routine when she was on 2 naps?
Layla