Can't lose weight!!

I officially think my body won't let me lose weight...I'm now 8wks PP (exclusively breastfeeding) and I have just over a stone of baby weight to lose. 
I've tried cutting out pretty much all of the cakes and biscuits (I have a massive sweet tooth) having smaller portions at meal time, drinking tons of water and coconut water. And generally just healthier eating. Also walking most days, and I haven't lost a single pound! 😔 
Any tips or advise? xx