Mothers milk is the best and safest for your baby and I commend you for exclusively breastfeeding your baby for 3 months. With regards to your travel, as far as possible, I would suggest you try to avoid top feeding and continue to breastfeed only. If possible, you may also express your breastmilk prior to departure, and feed the same milk to your baby. The expressed milk can be kept at room temperature for upto 6hrs. Top feeding has a lot of cons.... indigestion, diarrhoea and infection being a few. Any expressed breastmilk should be fed to baby via a steel cup and steel spoon, which should have been properly sterilised in boiling water for at least 5 to 10 mins. The same can be used when feeding a baby with formula feed, although I would suggest you hold it off for at least another couple of months. Bear of luck and safe travels!

Breast feeds are the best & safest for baby, especially during travel, as giving top feeds entail huge risk of infection (clean water, proper sterilisation, proper handling of utensils) while breast milk is protective against gut infections.