The thing about being a parent is that you really have to live through it to get to a point where you really can understand it. People who have no kids will not understand 90% of what you are going through, and having a girl who is now 3, I can say that so much of the first-time parenting that you go through in those first few months seems different from the distance of time and further experience.

It's certainly good to try to engage your baby with stimuli, but the simple fact is that all children develop along more or less the same lines for the first two years. Even after that, a lot seems to be out of the parents' hands. The classical music study has been thoroughly debunked, the high contrast toys are of questionable value and there's really little that seems to make much of a difference at all, except that there seems to be some correlation between extended crawling and good memory (so don't be worried if your daughter doesn't start walking right away; it might be a good thing).

The effort by parents to make sure their children don't end up disadvantaged is one that is milked by thousands of companies to their profit. For the parents, this means you end up spending more money than you need to on items you don't need and will quickly have no room for unless you have over 100 square meters of living space. The mantra "it will be useful if/when we have another child" is always invoked - which means you're going to have to spend a lot more money on storage boxes that will seal out the elements, or else you're going to find that you might not want to give the toy to the second child when you have one. We now have something like eight huge boxes (about 1 meter long, half a meter deep and half a meter wide) filled with toys, clothes, etc., and of course the bigger things are covered in plastic partially disassembled (the exersaucer, the bouncy chair, the baby baths - plural because our daughter hated the first two we bought, the mobiles, the activity mats, the baby gates, the training potty, the five different types of strollers, the different size car seats, etc.).

And, even if you buy some things in generic colors (black car seat, red stroller, etc.) so that it fits either sex for "the next time", you're still going to have to deal with the possibility that your next baby will hate something that you dropped a lot of money on (like a stroller, for example).