Luggage policies

Hi all,

I will be travelling to Thailand for the first time in a few days. My itinerary is Amsterdam-Bangkok-Phuket-Krabi-Bangkok-Amsterdam. So the return flight I have booked includes a personal item(backpack)and a hand luggage (both should not exceed 12kg)

Now, the issue is that I have booked flights from Bangkok to Phuket and then from Krabi to Phuket which include indeed a personal item and a hand luggage but their weight should not exceed 7kg.

I wanted to check what are my options if I want to bring more than 7kg (which will probably be the case). Can I pay for the extra kilograms in the respective airports? Or will this cause any issue with the airline? I am a bit stressed since it will be my first time there so I won’t to avoid any impediments.

Thanks!