I think you have to identify (and this something you can do with some soul-searching) that the "pressure" you are putting on yourself is working for you. The pressure can be a motivator in achieving your goals (no matter how high) and if this pressure is getting you closer to realising your dreams, then it should be taken as positive stress.
However, if this stress is stopping you from functioning normally, then it is alarming and you should see to it. Sometimes you cannot do everything and you have to make choices because of limited resources. It is no one's fault if you are unable to achieve everything and you should not take it to heart either. All the best!