None of this should be considered medical advice. Let's consider this as a totally hypothetical situation...
That being said, I'd be wary of taking advice from anyone over the internet about this unless they know the all details of your own particular situation. You've mentioned that you were "born with AS." That doesn't really give a reason why you have it. It could be because you were born with something called a bicuspid valve, or a unicuspid valve, or even something else. Sometimes valves are not only blocked, but leak at the same time too. You could also have other associated abnormalities with your heart as well, like an ASD or PFO (abnormal holes or pathways between chambers in your heart), kinks in your blood vessels, or even dilated major blood vessels which would also change your management. So, in going to random people on the internet, someone might give you advice about AS in general, but not knowing that you also have something else going on inside your heart too, inadvertently give you advice wouldn't be applicable to your own individual situation.
Regardless, if you were born with AS then chances are that you will eventually need a valve replacement at some point in the future. Your situation as it is now will change after this happens. If bodybuilding is something that is very important to you personally you need to let your doctor know about it. If you've been lifting against his orders you should let him know that, too. It might change his management of you, change the timing of surgery, or might make him order other controlled tests to see exactly how much you can exert yourself before you experience symptoms.
Again, none of this should be considered medical advice, and only your own doctor will know all your specifics, so only he can best guide you. Good luck!