Drop feeding? Dream feed?

So for the last 2 nights I was very very tired and decided to skip the 10 pm feeding figuring DD will wake when she is hungry and it will just change our schedule a little.  On the first night, she ate at 7:00 and slept from about 8 till 2:40 but last night she ate at 7 and slept straight through until 5 am!  While it was nice to get the sleep, it worried me because thats skipping 2 feedings essentially.  But on the nights that I feed her at 10 she only sleeps till anywhere between 2:30 and 4:30.  So what would you do?  Continue to skip the 10 pm feeding or add it back and hope that the time balances out and she drops the middle of the night/early morning feeding on her own?  I just fed her (she only took about an ounce and a half) and put her down for the night, not quite 10 but she was tired.  

Btw, she's 7 weeks and about 12 lbs at this point.  She has been taking about 28 oz per day but now with the last couple days shes only getting 23-25.  Im wondering if this might just be a growth spurt and she's just tired or if she isnt feeling well and sleeping more.  Thoughts?