Great Start but kgs now very slow to drop

Hi Guys, first timer with MFP. 5 weeks in. First week a cracker with 4 kg drop, followed by 3, 1.5, 0.5 and this week so far 0. My days used to comprise of zero, I mean absolutely no exercise to now daily 40 min brisk walks with my dog or 40 min on the treadmill, some days I do both. My eating habits were pathetic, in my mind I didn't have the time to eat with a busy career and young children. My days used to start with a Iced Coffee, most lunches I skipped as I didn't stop to take a lunch break, on my way out of the office I would grab 3-4 mini Cadbury chocolates and then when I arrive late home I would grab whatever snack I could find in the fridge or cupboard. This has certainly changed, now eating plenty and very healthy - approx. 4300 to 5000 kjs per day. My measurements are decreasing and I have dropped a dress size which is fantastic, I can certainly feel the difference. This in itself should keep my momentum going, it has and it will but just a little disheartened the last 3 weeks I have only dropped 1.5 kgs. Understand first few weeks usually bring the best results, will keep going as surely over time the kgs will drop. Love to hear anyone else in similar situation needing a little boost whilst kjs are slow to drop. Cheers!