Your answer lies not in a question of patentability, but in the document you claimed you signed with the company.
If it was a non-disclosure agreement, and if they disclosed the information to someone else who is now using it, you may have a claim against them from profiting from your invention.
You have 2 hurdles 1) was it a valid non-disclosure agreement that covered the subject matter and properly prevented its disclosure; 2) proving that they disclosed the information rather than someone else simply having come up with the same product themselves.
Ask your local county Bar Association for a referral to an attorney specializing in Trade Secret/IP litigation. You should be able to find someone who will provide you with a free consultation.
However, there are some important questions:
First, You must prepare a full description and sketches (Figures) and each must be dated and signed by you and and two witnesses. The description will say "Thingy A fits into Doohicky B as shown in Figure 1....", etc. Purpose and function(s) must be fully described. This puts YOUR stake in the ground for this idea. This is MOST important.
Second, you could visit an IP and present your description and sketches. The IP can execute the witness/dating/signing step with you if it is not yet done.
Third, is your idea patentable? Or is it reflected in, or contained in, prior art? This requires a patent search, which costs about $1000 unless you go to DC and do it yourself. This activity will disclose prior art which YOU (not the IP) then MUST study and understand to determine if "someone else was there first".
NOTE: IF you should proceed to filing a patent, and IF the examiner challenges your patent as falling under prior art (see 'Third', above, and those prior art patents WILL be cited to challenge you), YOU, and NOT your IP, must write convincing refutations to the examiner that all cited prior patents are unrelated to your patent application in function and operation. *I repeat*, YOU, and NOT your IP, must convince the examiner that all cited prior patents are unrelated to your patent application.
Understand that a patent will cost from $5000 to $25,000, and sometimes a lot mote. The descriptions of the nature and function of the claimed device must be presented in a defined format and the Figures must be rendered in a specific format. [There are draftsmen who specalize in preparing these Figures.] The IP would prepare the text, and YOU would have to review and approve EVERYTHING as being a correct depiction of your idea.
Understand that many, many patents earn no money, and there are offshore knockoff companies that will, and can, put a marketable idea into production and into the consumer marketplace quicker than you could imagine.
There are "Patent Services" that claim they will help you get your idea patented in an easy and painless fashion, but this is hookum. Perhaps, in your case, someone simply beat you, or your idea was stolen.