Advice on weaning

Hi there
I need advice on weaning my 8 month old baby. He is currently on Nan during the day and i breastfeed at night and mornings. However at night, he refuses to take the bottle and only wants to breastfed. My milk supply is not as great as it used to be and now he wants milk throughout the night as he is teething.

Any tips on how to start weaning?