Hey OP, I think you're portions look fine and I have lost weight on those sort of meals and I have a lower BMI than you.
Here's my tips. #1 Watch the snacks - I've noticed alot of I "think" I had 2 biscuits, plus a couple of slices of cheesecake (which is bloody lethal) a day for 2 days, plus a weekend away is doing a bit of unravelling of the good stuff you're doing.
Take a pic of everything that goes in your gob, not just the good stuff, be honest. If you intend to eat a biscuit take a picture of it, if taking pics keeps you accountable.
Tip 2. Weigh everything, so a heaped tablespoon of cooked rice is meaningless. You need to weigh the dry rice as it's more accurate, or if you need to do a family portion, weight the dry rice first (say you intend to have 20g dry and the 2x family members have 80g dry each then weigh it cooked after and give yourself the equivilent portion so 1/9th) same for the chutney, weigh it. (I used to eat peanut butter on toast and log it as 1tsp, when I actually weighed the bloody stuff turned out I was eating 3tsps!)
Tip #3 just move, get your 10k steps a day if you can. Pedometers are dead cheap. Obviously better if you can do some strength exercises even if its just using your body as a weight, with squats, press ups, burpees, sit ups etc, but if you just move around more it will help give your metabolism a kick up the arse.
Tip#4 drink your 2l of water a day, it is really easy to mistake thirst cues for hunger cues, so eliminate that risk by staying hydrated.
Tip#5 basically similar to Tip 1, just log everything. Stolen a chip of your partners plate, log it. Sneaky biscuit whilst making a cuppa, log it. Extra dollop of mayo on your salad - log it. Your mates poured you a wine... well you get the drift.
Also invest in digital kitchen scales so you can weigh absolutley everything.
Having said that 4.5kg is really good work so you're doing something right. Dropping the lot off quickly at once usually doesn't work anyway and people who have massive losses usually just end up yoyoing as it's too bloody hard work and unsustainable. Consider it a lifestyle change not a diet and set a realistic goal of months rather than weeks, with little mini goals. :)
Good luck OP.