First, congratulations to you and your wife for already saving so much at age 30, which is a remarkable accomplishment. While you missed the opportunity to put your savings into a tax-advantaged account, there are still many ways to increase your retirement savings.
You mentioned that your employer doesn't offer a match, so you might consider contributing to a traditional 401k or a Roth 401k. A traditional 401k allows you to take a tax advantage when saving because your contributions are deductible on a pre-tax basis. a Roth 401k, on the other hand, saves after taxes, but you will enjoy tax-free earnings and withdrawals at retirement.
In addition, you can also consider Individual Retirement Accounts (IRAs), which also offer tax benefits, similar to a 401k. If you qualify, you can also contribute to a traditional IRA or Roth IRA. In addition, you may want to consider using a tax-advantaged investment account such as a Health Savings Account (HSA) or a 529 college savings plan.
In summary, while you may be missing out on some of the tax benefits of saving, there are still many other options available to help you increase your retirement savings. I recommend that you speak with a financial advisor or retirement savings specialist to help you choose the best savings option for you.