As I understand it it could be a problem for T if you are doing twice a month thing. Mostly ppl go once/ twice a week.
So T would have to keep the hour for you even when you are not coming or find somebody who also comes once every 2 weeks to share the time slot with.
However if you wish to continue like this she should be able to offer you a regular hour. Otherwise I would try to look for another T. Cause I agree with you that this is harmful to you therapeutic relationship.