Major anxiety issues while flying?

I'm flying this weekend on two 3 hour flights. The only time where I get really anxious is when we're either taking off or landing. When my anxiety kicks in it gives me the sensation of having to pee urgently, and am fearful of not making it in time. My question is, would I get in trouble if I went to the bathroom even though the seatbelt sign is turned on? Like, if we're landing and the sign is on, could I still go if I can't hold it?