I shower twice a day, wash properly, I have tried every antiperspirant going and I still smell of BO!?

Basically, I sweat quite alot, If I get nervous or general exercise i sweat loads, especially underarms. It gets to the point where its embarrassing. I put on a nice polo shirt and within 30 minutes the arm pits are drenched! I shower twice a day and wash properly but I can still smell the BO on myself which is not nice when I go to work etc.. I have also tried every antiperspirant going and they worked to start off with but now just don't work at all?! If anyone could help me with new advice I would be much grateful! Thank you :)