It is not reliable, from rely:
Reliable, a. Suitable or fit to be relied on; worthy of dependance or reliance; trustworthy. A reliable witness to the truth of the miracles." A. Norton.
Rely: To rest on something, as the mind when satisfied of the veracity, integrity or ability of persons, or of the certainty of facts or of evidence; to have confidence in; to trust in; to depend; with on.
nor is it dependable.
Dependable, a. That may be depended on; as dependable friendships
The definition of depend highlights why:
To rely for support; to be conditioned or contingent; to be connected with anything, as a cause of existence, or as a necessary condition; -- followed by on or upon, formerly by of.
To trust; to rest with confidence; to rely; to confide; to be certain; -- with on or upon; as, we depend on the word or assurance of our friends; we depend on the mail at the usual hour.
You rely upon the wages you earn from an unstable job to support you and your lifestyle. I believe that's the point, right?
However instead of writing "not _____" I'd suggest using the prefix un-, which also negates, as in unreliable or undependable. This means instead of writing the sentence as you suggested you'd write something like:
I am currently working for one company but the work there is unreliable so I am still looking for other opportunities.
This is purely stylistic preference though. The phrases "is not reliable" or "is not dependable" would work here too.
Webster's Revised Unabridged 1913 (Except as specified below)
The American Dictionary of the English Language by Noah Webster, first published in 1828. (Steady, rely)
American Heritage Dictionary of the English Language, Fifth Edition (Undependable link)