Hi
1) Since you have been employed for about 8 months and given the fact that as per terms of your appointment letter, the probation period is for six months, you will be a permanent employee in eyes of Law as you have worked beyond the stipulated probation period.
2) Your Human Resources Department cannot take umbrage on the guise that you remain a probation employee till your employment is confirmed.
3) The legal position is that Confirmation of an employee as Full time employee in writing is NOT Mandatory in eyes of law whereas in contra, if an employee is continued to be in Probation, it is mandatory that the employee be informed in writing that his services are NOT Confirmed and that his probation period is extended and in the said letter, the employee's consent for extension of probation must also be obtained in writing.
4) Since you have been employed for 8 months which is 2 months over and above the probation period, it is an automatic confirmation that you are a permanent employee.
5) In your case, though it is an "At-Will" Employment where in either side is liable to give 60 days notice or pay in lieu thereof, by default, the company is liable to pay you (Since you are yet to complete 1 year) the following as full and final settlement
a) Monthly salary till last day of working and
b) 60 days notice pay (full salary+P.F, and NOT Basic pay)
6) Also if there are more than 20 employees in your organisation which is being shut down, the company is liable to pay additionally 15 days basic pay for every year of service rendered by an employee (however this might not be applicable to you as you have only 8 months service in the company.
Hope this information is useful.