Ok, let's give this a shot then.I'm making some assumptions here, so if I get anything wrong you can redo the calculations with corrected numbers or post the corrections and I or someone else can help.

I'm assuming you have $70k income before HSA or 403(b) deductions. If you also pay health insurance premiums out of this amount then this would reduce your taxable income further.

I'll assume to can afford to contribute $6000 max to Roth and $13,000 to your 403(b) for a total of $19,000 or the full $19,000 max to the 403(b) plus tax savings on the additional $6000 which will be contributed to Roth.

I'm not super familiar with the child tax credit, so you'll want to run this through some tax software or a demo return to confirm my calculations. Or hopefully someone with kids can chime in.

With maxing Roth:

$70,000 income

-$7000 HSA contribution

-$13,000 403(b) contribution

-$18,350 HOH standard deduction

=$31,650 taxable income

($31,650 taxable income - $13,850 in the 10%) x 12% tax + $13850 x 10% tax = $3,521 total tax liability - $2000 child tax credit x 3 children = $479 refund (this is under the $1400x3 = $4200 max refundable amount, so you'll get the full $479).

Without maxing Roth

$70,000 income

-$7000 HSA contribution

-$19,000 403(b) contribution

-$18,350 HOH standard deduction

=$25,650 taxable income

($25,650 taxable income - $13,850 in the 10%) x 12% tax + $13850 x 10% tax = $2,801 total tax liability - $2000 child tax credit x 3 children = $1,199 refund (this is under the $1400x3 = $4200 max refundable amount, so you'll get the full $1,199).

So, by contributing the additional $6000 to your 403(b) you get an additional $720 refund. $720/$6000 = 12%, so your marginal tax savings is 12% (this makes sense since your marginal/top tax rate is 12%). The $720 additional tax savings should be saved in Roth.

This implies current spending of:

$70,000 income

-$7000 HSA

=$63000 before FICA tax

-$63,000 x 7.65% = $4,819.50 FICA

=$58,180.50 FICA

-$19,000 403(b)/roth savings

+$479 tax refund

=$39,659.50 earned/spent.

Does that seem in line with your current spending?

Using excel (or in my case, the free Libre Office program) Future value formula, your current $58,000 savings, $19,000/year savings, a 5% real (inflation adjusted) return, which is maybe slightly low, but also not as pessimistic as some people say we should expect, I get that you would have $965,327.41 at 60 or $1,337,016.56 at 65. I didn't include any employer match you might get in your 403(b) in these numbers, so they could be higher if you get additional money from your employer. Keep in mind that while these are very precise numbers, the output is only as good as the input, so since we have no idea what the future return will be these have to be considered very rough estimates at best.

Using a 3.5% safe withdrawal rate this would provide you with $33,786.46 or $46,795.58 per year respectively. You'll surely see the 4% "rule" bandied about around here instead of the 3.5% I've used here. For that, I'd encourage you to take a look through the posts at

https://earlyretirementnow.com/2016/12/07/the-ultimate-guide-to-safe-withdrawal-rates-part-1-intro/.

Along with your pension I think this confirms that you're in the right range with your 60-65 estimate. You'd probably have enough at 60 if your pension started then, so you'd just need to keep working beyond that to cover the pension shortfall and health insurance costs until 65. As you get closer you can also see how secure social security is looking and that might let you retire sooner as you get a better idea of how much and when it will pay.

Either way, under current tax law, since you'll be filing single at that time your $40k of income if all your income was taxable (from the 403(b) and pension), you''ll likely be in the 12% bracket and unlikely to be in a higher bracket. However, taxes are scheduled to go back the pre 2018 brackets in 2025, so that might put you in the 15% bracket, which would indicate you should go with Roth now, but it would be close.

I think I would consider two factors 1) Will you be moving to/from a no or lower income tax state than where you live now when you retire and 2) do you think taxes rates are more likely to go up or down in the future. Since you're pretty close to Roth/traditional not making a difference either way (equal marginal rates now and in retirement)), I think I would probably do a bit of Roth now unless you expect state taxes to go down for you or federal taxes to go down for everyone in the future. Be sure to reevaluate if/when your income increases in the future.