• holding your baby across your lap, using the opposite arm as the breast he is feeding from
holding your baby across your lap, supporting him with the same arm as your breast
• You could also hold him underarm, sitting cross-legged on the side of the bed, or using two chairs at right angles.
This means that you will need to hold your baby across your lap to feed on one breast. Then to feed from the other breast, you'll need to hold your baby under your arm. That way you can hold him with the same arm and hand for both breasts.
If you find a position that works for you and your baby, then it is fine to stick with it. But as your baby gets older and you become more practiced, you will probably want to change positions. Much will depend on where you are and what you are doing.
If you have mastitis or blocked ducts your doctor or breastfeeding counselor may advise you to hold your baby in a different position.
This may be good advice, but if it works for you, it will be because you are able to help your baby get a better mouthful of breast. It will not be because changing positions causes your baby to drain a different section of your breast. All sections are equally well drained if your baby is latched on well, whatever position you use.