This has nothing to do with you personally OP, but when women I know IRL have complained that they were bored while SAH because they were too "educated and intellectual" I always thought to myself, "if you are so smart then why can't you think of something to do."
It is one of those statements that often leave some SAHMs feeling put down or self conscious if worded the right (wrong?) way. Especially when it is dripping with that "it may be good enough for *you*..." tone of voice.
In all seriousness, I do get the need to stimulate your mind. I think there are so many factors that make it difficult for some women to make the adjustment to staying at home without feeling bored. Often being at home makes it necessary to find a whole new set of people to hang out with (because everyone else is at work all day). And getting to know other moms usually happens by discussing kids. Once you get to know some women who you have things in common with it is easier to get beyond the mommy talk. That took me 5 YEARS to do. Sometimes the only common ground I have with people is the fact that we both have children.
Also, some people are self-motivated when it comes to keeping themselves fulfilled, others are not. Neither way is the right way, we are all unique. Some need a little help looking outside of the way they used to do things.
In reality, there are so many interesting and wonderful things to do in a day. And finding ways to do them while caring for children adds a whole new level of creativity. What are your interests? What have you always wanted to learn? Now is the time to do it. Not only do you have the ability to create your own schedule (with some limits of course), but you will also be setting a great example to your dd in doing so.
For me, I set a goal of something new to learn each year. One year I learned to knit. Another year I learned to build simple things. Then I learned about renovations, now I am trying to tackle growing things (my second attempt, the first one didn't go so well). Aside from that I love to research things. It is a great hobby, and since becoming a mom (4 times) I am never out of subject matter. I also read as much as ever (generally I have 4 books on the go) and am sure to devote time each week to other things I enjoy (physical activity. thrift store shopping, knitting, whatever other handiwork I am into ATM, etc). And generally I manage it all with only being away from the kids 2 hours per week. I consider working it all out to be like Tetris. Just rearrange it all until it fits
It is harder with a first (or only) child because you are really their main source of entertainment as well as their playmate. Also, you are in the beginning stages of figuring out how your Tetris puzzle will fit together best. Give it time, figure out what you miss the most and think about all the ways you can get that underlying need met. It may not be in the way you are used to, but exploring all the possibilities is the very best part!