Krisp, I don't want to be cynical, but the MCHN conferences are often sponsored by formula and baby food manufacturers. I am not a health professional, but I think you find that many people who are will tell you that the latest research does not suggest that solids be introduced at 4 months. The recommended age is always going to be contentious.

As QM says, BLW is being talked about a lot atm, although not a new concept and it makes a lot of sense. When babies are ready for solids, they are able to feed themselves finger food. The idea of starting with mush was only introduced relatively recently, when the age that we started feeding babies dropped (to 3 or 4 months at various times). By 6 months, many babies are ready for food and can eat finger food. There is great information out there about BLW and in fact, most of us with more than one child find that after the first we pretty much do BLW by instinct and necessity anyway.

As for your DD not being interested, my first DD was 8 or 9 months before he really wanted to eat anything, and about 1 before he ate any quantity of food. There are always going to be babies who aren't ready until well after 6 months. Which personally makes me wonder why so many people are keen to recommend starting solids at as early as 3 or 4 months. There is no harm done by not starting solids as soon as they are ready.