I am considering stopping breast feeding my 5 m...

I am considering stopping breast feeding my 5 month old as he is still hungry after his feeds. This started when bubs started sleeping 12-14 hours a night, my milk supply has reduced. I have enough milk for the first morning feed but when he feeds next, he is left wanting more. Therefore I have been giving him formula during the day and then the final bf at bed time. I'm now deciding whether I stop bf all together or continue on with 2 bf and 2 formula feeds per day. As this is my last child I'm a bit anxious in stopping breast feeding. I fed my last child until 6 months and it didnt phase me when I stopped but this time I'm really unsure. Has anyone else felt this way?