Not very experienced in planning! Opinions needed September

Hello everyone. I’m not great when it comes to planning abroad trips, but I’ve been gifted some money for a honeymoon which originally was going to be delayed. I am looking somewhere in east Asia. Bali, Kula Lumpar, Langkawi. Dates are 10th to 25th September. £3.5k budget. We are flying from London (any)

I had originally planned Langkawi then KL for 7 days each. I know my fiancé loves the idea of a relaxing (beach) area and then a city. My concerns are the following and would love extra feedback.

• Bali was an option but I hear the food causes something called the “Bali-belly” where you get food poisoning.
• I hear bali people travel to different hotels. Would this make us tired?
• the weather doesn’t seem great in Langkawi which is a beach location. I am very concerned about this actually.
• I found some hotels, but any recommendations would be fabulous.
• is there anywhere else around that location ( south east Asia ) which could be good?
• is 7 days too long in KL?

Ultimately, some general advice would be great. We’ve had a difficult year in terms of wedding prep and I genuinely want to give her the honeymoon she deserves.