Your title doesn't matter. What matters is whether the description of your duties in the letters matches the duties stated in the NOC.
If you can't get all the details you need from the employer itself, a supporting letter from a direct supervisor (best), senior colleague (decent) or peer colleague (marginal) may help. However you should make sure that anyone who writes a letter for you has a reasonable basis for knowing the details they are providing in the letter. If it's not obvious why the letter writer should know your duties, the letter writer should explain it. For example your direct supervisor obviously knows your duties, but a peer colleague does not obviously know your duties, unless for example you worked on the same team, or you were responsible for delivering work product to that colleague, or something like that, in which case that should be explained.
The purpose of the letters is to show the reviewer that you have the experience you claim to have, and the burden is on the applicant to show it. Do not assume that a reviewer will make any connections you do not explicitly establish even if they are logical connections. Do not assume that a reviewer will ask for clarification or additional information. They are under no obligation to do so.
Nobody knows how many points you can get for your experience. You will get as many as the reviewer gives you credit for, and the credit will come from clear and convincing letters and/or supporting documents.
