Yes I understand. I was worried about that when my DS moved to longer sleeps and longer "A" time (ie/ 2.5 hours of A time, pushing to 3 soon) and asked on the EASY and the Feeding boards about what to do about 4 hour feeds, and I was told that feeds aren't 4 hourly anymore. No one ever really told me how often to space out the feeds, but I don't go by 4 hourly anymore at 6 months. I keep them as close as I can, but I think of them more as a breakfast, lunch, dinner and bedtime feeds. In our case, that's 630ish when he wakes up, then sometime between 1045 and 1130 depending on nap, then sometime between 300 and 400 dep on naps, and then one right before bed, regardless of how close that is to the last one.
Don't know if that's "right" but as I said, that's what I was told on the EASY boards. Not saying you have to do this, or that you should of course, just making a suggestion on how to get to the bedtime stretch! I don't think that 30 minutes at this age, esp when she has solids, will make a big prob with the bottles -- but, you know your LO best!!