Is my employment agreement enforceable or am I employed at-will?

I am a medical provider in Oregon. In 2016, I signed an employment agreement that stated my employment could be terminated without cause by any party with 90-day notice. I signed, but have confirmation from HR (in late 2022) that the CEO never countersigned. If it matters, in 2018 I was promoted and had my title and compensation changed but do not recall signing a new contract and HR didn't have anything on file.

In 2022, I was forced to sign a new employee manual that states:
'I have entered into my employment relationship with *** voluntarily and acknowledge that there is no guaranteed length of employment. Accordingly, either I or *** can terminate the relationship at will, with or without cause, at any time, so long as there is not violation of applicable federal or state law.

I understand and agree that, other than the Chief Executive Officer (CEO) of *** or
designated representative of ***, no manager, supervisor, or representative of *** has any
authority to enter into any agreement for employment other than at-will; only the CEO of
*** has the authority to make any such agreement and then only in writing signed by the
CEO.

This manual and the policies and procedures contained herein supersede any and all prior practices, oral or written representations, or statements regarding the terms and conditions of your employment with ***. By distributing this handbook, *** expressly revokes any and all previous policies and procedures which are inconsistent with those contained herein.

I understand and agree that nothing in the Employee Handbook creates, or is intended to create, a promise or representation of continued employment and that employment at *** is employment at-will, which may be terminated at the will of either *** or myself. Furthermore, I acknowledge that this handbook is neither a contract of employment nor a legal document.'

I want to leave the company and finding work in my field that can wait 90 days is difficult. Did the handbook nullify my employment agreement, was it even enforceable with HR confirming that it was never fully countersigned and does a title/position change nullify the previous agreement?

Thanks!