Onc.heaven scent flat pseudobulbs help!!

[sharon lynn]

.. I could use some help . I got a Heaven scent onc . From a nursery last summer (August). The leaves are nice & green & getting tall but the psbulbs are going flat ! . It’s in a 4” pot . I have a layer of spagnum moss on top of the medium (small bark & perlite ,that’s how I got it) . I spray the top moss when it becomes dry ..maybe 2 times a week & water whole plant weekly .. I weakly fertilize once or twice a month . I have it in front of east window & for last 2-3 weeks a grow lamp. I don’t understand why the pseudobulbs are flat! Am I doing something wrong? Any help , advice or ideas are greatly appreciated..