Is it too late to add two medical payments?

No, it is not too late, but the remedy depends on your situation.

If you have not attempted tot e-file your return, you can log into TurboTax, and add the amounts to your medical expenses in itemized deductions.

If you have already e-filed, you will need to wait until the return is accepted or rejected.  If it is rejected, you can simply add the missed amounts and try to e-file again.  If it is accepted, you will have to file an amended return. Here are the steps to follow to file an amended return: How to File an Amended Tax Return with the IRS

It is important to note, that medical expenses are only deductible once they exceed 7.5% of your AGI.  See this helpful article for more information: Are Medical Expenses Tax Deductible?