Candidly, there must be another issue. I have three bikes - one high end bike, one dedicated time trial bike, and one cheapo, heavy bike - my Specialized Sequoia. I have had the latter bike up to 36.9 mph on the flats. You should have a great aerobic engine and tremendous leg strength from rowing. I know, in that my kid had a full ride to Syracuse on a rowing scholarship and he could pump 1000 pound leg presses for quite a few reps.
I wonder if you have the proper size bike, and I wonder if you were fitted properly to the bike. So many bike shops don't have a clue as to how to properly fit a bike - a procedure that can take up to two hours or more. AAMOF, I have three hours of fitting invested in my time trial bike, and it fits like a glove when I race it.