Hi M.,
Yes feeding is so confusing! (and sorry this is so long!)
Ok here are some of the "rules" or guidelines,
Allergies: allergies to foods develop after repeated exposure. so like allergies to wheat will not happen immediately, it takes multiple times feeding him that his allergy shows. Sometimes it is immediate, but most of the time it is from repeated. The next question to answer is do you have any allergies on either side of the family? Then just be mindful of those things, like nuts. (I am waiting until 3 yrs for peanuts - because I have allergies on both sides of the family to other kinds of nuts).
The best way is to offer the same thing for five days before you introduce something new(you can mix in with things that are already ok). So if he eats egg yolk fine, add cheerios with the egg. Then if there is a reaction you will know it is the cheerios not the egg. It's really so you can keep track, like if he has a reaction you will know what it was and not have to back track or start from scratch.
Then you have my SIL, who threw caution to the wind and gave her twin girls everything, and they are fine. I on the other hand am waiting on a year for dairy, wheat, and egg whites. Yes, that makes it very hard, but I feel a year of limitations is worth a lifetime of none! For my SIL everything is fine, and most kids it is.
My son is off and on with egg yolk. Try different things, scrambled and fried (which ends up kinda scrambling) and hard boiled. Like me his a moody eater.
It sounds like everything is fine. You are doing a great job! If you'd like more info, check out Dr. Sear's site, also babycenter has good articles too that are pretty right on. Just FYI, doctors do not have extensive training in nutrition, so if you feel you are at odds with your ped, you are not alone.
As for meat, I read in multiple places that they should be 8 to 9 months because their digestive track doesn't have all the enzymes to break it down. If you have already begun, just hold back from now on. And reintroduce later (I think you said he is 7 mo).
As for cheerios and stuff, I have seen kids with few teeth work those out just fine. I started by cutting them in half, and that worked. They just gum them.
Unfortunately I think food stuff is half instinct and half knowledge, with a pinch of trial and error.
I read Super Baby Food (but I don't make her porridge), and What to Expect Baby's First Year. I also use Dr. Sear's site and BabyCenter.com. Oh, and I tend to read a lot of magazines, which is good and bad. Sometimes they are a little sensational - so you have to use common sense.
Best wishes to you and your family!