[Grammar] Having

[Raymott]

I'm not sure I understand. Do you mean:
-her plan was to lose ten pounds before summer
-she didn't lose ten pounds before summer, but she did lose ten pounds during the summer?

And this is another example of where she could have said, "I had planned to have lost ten pounds by summer. But I didn't, so I couldn't wear my new dress to the Summer Ball."
The index time in the past is the time of the ball. The two previous times are the end of summer, and the time of planning the weight loss.