Karen,
Most mums give milk and then solids about 1hr after. As my DD can't stay awake that long I always give my DD solids and then milk straight afterwards. But I think that all depends on what you think is right.
How much solids are you giving her, and how many ozs of milk are you giving her? Do you give her a dreamfeed?
Was she always a tummy sleeper?
With the naps and food. She is overtired, so won't be taking quite as much food, so you will have to work on her naps.
I really don't think she is going to bed too late as 7pm is the norm for most mums, but if she is tired, try putting her to bed at 6.30pm, until she gets back into the routine.
With the naps, does she wake after 40mins and then won't resettle? If so, do PU/PD until next feed time if necessary, every nap. Reassure her with quiet words, saying like mummy is here, I'm not going anywhere, you just trying to go to sleep. Put down as soon as she stops crying, and stroke her head with quiet words. As she will be hitting 7 months, maybe it is the case of seperation anxiety. I would not recommend CIO, as this will break the trust of you and your daughter, it may cause further problems. This may take 3 days or a week or maybe longer but you have to be consisent.