A few disjointed thoughts:
1. FI is different than RE. FI in and of itself has tremendous value, because it enables you to flip the bird at any job or situation you don't like for any reason. It is in your long-term best interest to figure out a minimal-FI number -- the "I can quit without losing the house" number -- and prioritize that. Regardless of when (or if) you want to RE.
2. Your needs/goals/capabilities will change over the next 10-15 years. Again: it's always better to find yourself at your planned FIRE date and realize that you don't want to quit than it is to want to quit and realize you still have years to go before your planned FIRE date.
3. Pay attention to
@Zikoris' post, regardless of whether you agree with it. Much of our spending is based on how we define having a "good" life and giving our kids a "good" childhood. The more you can challenge your thinking on that score, the more you can lower your base expenses and free up savings -- or, at a minimum, have confidence that the things you are spending on really do add value to your life.
4. There is not one path to FIRE. Many people choose to go part-time when their kids are young and live a more bare-bones budget because they prioritize having the time with their kids. Other people don't. You get to choose how hard you work and for how long.
5. You also get to choose how busy your life is. If you are working long hours to earn the money you need to pay for private school and lessons of every type and travel sports, and then are constantly exhausted because you're spending your life chauffeuring your kids around to everything, that's on you. Kids don't actually need any of that stuff. So if you are choosing a lifestyle that feels overwhelming, change it.
5.a. Corollary to the above: when you have multiple small kids, everything is some version of suck, because they truly need a tremendous amount of time and attention. In most cases, it does get easier as they get older -- at least, if you don't fill every waking hour with activities -- which in turn makes the juggle feel more attainable.
6. If you're actively thinking about FIRE vs. lifestyle, you're ahead of 98% of the population, so congratulations.