Lori-
Use this tool:
https://infocovid.viaggiaresicuri.it/returningtoitaly.html
You will be entering Italy from The Netherlands and have been in USA prior.
It looks like you are OK to enter and your test will still be valid. You actually don't need the test if you are vaccinated. Don't know if needed for Amsterdam. Length of time you are in that country doesn't matter.
Based on your answers, you can enter Italy. There are special provisions in place if you are travelling from Canada, Japan or the United States.
Read carefully the information provided below.
If you are travelling to Italy after a stay/transit in a List D Country (other than Canada, Japan or the United States) in the previous 14 days:
You must fill out a digital Passenger Locator Form (or, in case of lack of necessary technology, a self-declaration) and present it to the carrier or any other authorised person, either printed or on your mobile device;
You must prove that you have undergone a molecular or antigenic test, carried out by means of a swab, with negative result, in the 72 hours before you arrive.
As soon as you enter the national territory, you must inform your Local Health Authority of reference.
Bear in mind that airport transit is allowed, provided that you do not exit designated areas.
Once you have reached the address indicated in the dPLF, you must self-isolate for five (5) days.
You must undergo another molecular or antigenic test, carried out by means of a swab, at the end of the 5-day self-isolation. Exceptions are indicated below.<<
If you are traveling to Italy from Canada, Japan or the United States:
You must fill out a digital Passenger Locator Form (or, in case of lack of necessary technology, a self-declaration) and present it to the carrier or any other authorised person, either printed or on your mobile device;
You may present to the carrier, or any other authorised person, a Covid Certificate (also known as Green Pass or Covid-19 Green Certificate) or equivalent certificate, issued by your local health authorities in Canada, Japan or the USA, showing proof that you have either:
been vaccinated against COVID-19 with an EMA authorised vaccine and you have completed the prescribed vaccination cycle since at least fourteen days;
received a negative result of a molecular or antigenic test carried out in the 48 hours before your arrival;
recovered from COVID-19 and you are no longer under prescription of self-isolation. <<