Claim for Regularization in Centre Government Department

Sir, I have been working in an autonomous dept. under central govt. for more than 3 years with continuous service on contractual basis. I am working as a LDC in the department and also a member of some vital committees. I am getting band pay plus grade pay, EL, CL, ML (EL & ML are being added every year) and medical reimbursement. My selection was done after following same recruitment procedure as for regular post (No back door entry). The contract was made for 1 year and it is being extended subsequently according to the work needs and performance. There is no contractor between employer and me. In my appointment letter it is mentioned that candidate can not claim for permanency in future. Meanwhile, last year recruitment for regular post was done and when i applied for the same, my candidature was cancelled stating the reason of 3 months overage, whereas when i had joined the department and when the vacancy was available i was fulfilling the age criteria. The admin, after completing the whole recruitment process, declared one post of LDC, out of three vacant post, as None found suitable. Again the recruitment notice for this and other vacant posts has been published and scrutiny is being done of received application. Sir, my rights on this may kindly be advised and can i claim for my regularization in the department? Please give advice on this to me, i will be very thankful to you. Thanking you with anticipation.