I wouldn't think of it as solids making up for the milk, but what could happen is that if she doesn't get as much milk during the day, she'll make up for it by nursing more at night when you're together, which will also help stimulate your supply back to its usual level. So if you do have a supply drop, that might be a time to cut back on solids in the evenings/weekends to let that compensation happen. But that doesn't mean that you should never give solids in the evening - if things are on track with your supply it's fine to give solids when you're together, but you want to nurse before giving solids so that the solids don't interfere with nursing. In terms of finding a doctor, well, if you can find one that is knowledgeable that's great, but if you can't and if you feel like you have enough support from other places (the forums, or a local La Leche League group for example), if you don't feel like the doctor is actively antagonizing your breastfeeding efforts I don't think it's necessary to switch. I mean I basically ignore my doctor when he gives me advice that I don't find breastfeeding-friendly, but I still think he's a good doctor overall.
As far as STTN - I do think that nighttime nursing has a big impact on supply, so especially if you find yourself struggling with pump output I think it can help a lot to dream feed, and it's probably easier to do than to try to squeeze in yet more pumping time.