It certainly is big enough to bloom, never heard of this problem. It isn't moving around in that pot, rubbing the roots at all, is it. ? Are you regularly fertilizing? Hope someone has the answer for you.
The odd thing is that the spikes still look green. They haven't died off or turned yellow. How long have they been there? Some orchids start to spike and then don't do anything for several weeks. The first thing I would consider is light. Is it possible to give it a little more light or increase the length of time that it receives light? Good luck.
Don't dispair. I had a vanda that behaved this way. She aborted 4 tiny spikes and finally succeeding in blooming on her 5th try. Since then she's bloomed regularly. My vanda has semi-terete leaves and she was about the size of yours when she first bloomed. Your plant looks healthy and so does her roots. The leaves look a little dark which usually indicates underlit conditions. You might try bumping her to SLIGHTLY higher lighting conditions or to a spot where she receives a few more hours of similar lighting. Your Vanda is beautiful and she should bloom for you soon.
I have found that my Vanda will abort a flower spike if I miss a watering on time or the humidity is too low. I have had mine for several years now, and that is the only time it has aborted flowers