For breast-feeding at early stage, it is better to feed around 25mins for each side. Too long duration only causes tiring and uncomfortable feeling for both mom and baby. One thing you have to note, it is usually more frequent (every 1.5-2hrs) to bf the baby for the first 3 months pending on individual one.
Since no one can assist during bf, you have to relax and be cheerful in order not to affect the milk quantity.
Your baby will "tell" you if he/she is hungry, don't worry and don't give up!!