Your numbers do not check out.
>Child support: The minimum guideline is 33% of income for a single child, non-deductible.
Where are you getting the 33% figure from? Using the figures from https://en.wikipedia.org/wiki/Cost_of_raising_a_child, see that for the $59,410 to $102,870 before tax income group (Average = $79,940), the average spent per year is 13,050, or 16.3% pre-tax. The percentages for the Less than $59,410 and More than $102,870 groups are 24.7% and 12.0% respectively, which suggests that as your income goes up, the percentage devoted to rasing a child goes down.
> US/CA taxes take ~55%, so that leaves 12%. If you have a great tech salary of $150k,
How are you getting 55%? According to https://smartasset.com/taxes/california-tax-calculator, at $150k salary, your effective rate is 32.3% and your marginal rate is 34.75%. This includes FICA. Playing around with the numbers, even a salary of $500k, your marginal rate is only 48.65%.
>that leaves you with a living budget of $1500/mo.
Using the numbers from the sources I've mentioned, you actually have a budget of $6287, and that's with 2 children.
gross income: $150,000
take home (includes federal, FICA, state): $101,545
cost of 2 children: (234,900 / 18) * 2 = 26100
remaining: $75,445/yr, or $6287/month