For estimating stock market returns, I use this site for historical data on the US stock market:
http://www.moneychimp.com/features/market_cagr.htmFor the last 146 years, the CAGR is 9.15% nominal (not adjusted for inflation) or 6.96% real (inflation adjusted). The CAGR is a more true representation of expected returns than just a simple average. Obviously, we don't know what the future holds, but we might as well use what data we have available for planning purposes. It's obviously not guaranteed but likely more realistic than 5%. In your case, you want to use the nominal return (9%) to compare to your debt, since your debt payments are fixed (not adjusted with inflation like other expenses). For determining your needs to meet your other expenses, I'd use the 7% number.
It's not clear if you're taking into account the taxes saved by investing in an IRA or 401k. If you're in the 12% bracket, you'd save $1320 in taxes on $11k into 2 IRAs or $2200 in taxes on $18.5k into the 401k.
Keep in mind that there are ways that you can access your IRAs/401k's without penalty before 59.5, so you don't have to assume that money is tied up until 20 years from now. You can access your 401k if you retire when you're 55 or older and leave the money in that account. For your wife, that's only 7 years away if she's planning to stay at the job that long. That's for a 401k only and does not work for an IRA. There's also something called SEPP/72t that allows to to take money out based on some approved IRS methods, but you have to continue doing this until you're 59.5 or you will be assessed a penalty on all money taken out. The most popular option is a Roth pipeline, but this requires 5 years to get started so may not make as much sense in your situation. Here's a post with more info about these:
https://forum.mrmoneymustache.com/investor-alley/how-to-withdraw-funds-from-your-ira-and-401k-without-penalty-before-age-59-5/ I agree with everything Dicey said. I don't understand why you'd want to pay off the 1.9% car loan when you have 0 savings and could be making 9% in the market. The student loan rate is a bit higher, so I could at least understand paying that down more so, but I'd still favor retirement investing over it.
What is your house worth? What does Zillow or a similar website say it's worth anyway? You mentioned that you re-financed recently but also that you've been making extra payments and your balance is low. So it's possible you could still get money out at a lower rate and pay down the SL debt with it, but we can't say without knowing what equity you have in the house.
I also would try and sell the car and get a few year old car in the $15k range, or more ideally, an older car in the $5-10k range. I have a perfectly reliable car that's 13 years old with 115k miles on it that I bought for $6.6k about 8 years ago. No, it's not luxurious, but it gets me from point A to point B which is all I need. Even with higher repair costs on older cars, I think it's hard to make up for the ridiculously high purchase price of new cars. I also bike more miles than I drive now, so that helps keep costs down, both on gas and wear and tear on the vehicle. I figure my car has cost me about $1250 a year for the last 8 years. This is purchase price and maintenance/repair, but not including gas. I think this is one area where you could seriously save.
Final note: Don't forget about health care expenses in retirement. You mentioned that your employer pays 100% of this right now and your most recent math doesn't seem to add this back into your retirement expenses. You may be eligible for ACA subsidies if they're around then, but it'd be risky to plan on that. You mentioned you might keep working, so it may not be a concern, but something to keep in mind.
Sorry for the wall of text. Good luck and Happy 4th everyone!