If you are the only programmer then it is not unusual at all that you are likely underpaid. If there are other developers you have to find some method of determining what they are paid ( at least ballpark ). If they are all paid similar to you and there is a waiting supply of peope at your experience for the job at your salary then -- you aren't underpaid. Network with other developers in your area, talk with a recruiter, etc to find out what the range is.

If your company views programming as a cost rather than a profit center, it adds to your difficulty in getting median or better pay.

Finally, I get from your posting that you are probably in a very small ( or only developer ) programming group with your company; and it is probably your first job. Your frame of reference for what is expected from a Senior Developer or Architect is probably not quite right.

For instance, in New Jersey, USA most real senior developers are expected to have 10+ years of experience and to be real experts on the primary technologies they utilize. To have completed life cycles on numerous ( 7+ ) projects -- possibly less if projects have been extremely large. Architects are expected to have even more experience and breadth than that.