How to lose weight healthily ?

I'm in my third trimester and am 34 weeks and so far I have gained 16kg (35.2lbs) It has started to get me down about how much I've gained, it's quite noticeable in my face arms and thighs and I want to work out or maybe lose just a bit of the weight but healthily so it won't hurt baby.

I thought I do eat healthy, I eat a lot of fruits and veggies and nice portion meals and a lot of chicken but for some reason I keep gaining ( could be water weight I guess I do drink 3 litres a day of water alone). All though I do indulge in a craving every now and then.

I just don't know what workouts are safe during pregnancy and good ones to do, I don't want to strain myself too much and it is summer in Australia and so hot at the moment so going for a walk during the day and even up until 8 at night is out of the question ( I over heat easily).

So does anyone have any ideas or things they have done which have worked for them plus any exercises or meal plans to help ? Any tips are welcomed!

Thank you ! xx