Post baby weight loss

I lost 30kg 4 years ago with my 4th baby, just had my 5th and I need to lose excess of 10-20kg
That sounds like it will take forever 😭
So far my BMR is 1800
I'm eating 1500
Exclusively breastfeeding so extra 300 accounted for that
Burning about 500-600 in daily exercise
I think that's a pretty safe plan to keep my milk supply. All up daily I should have a deficit of 1100ish
I've been doing this a week and won't weigh myself until I've done this for a whole month.
Please encourage me or share your knowledge I'm almost 3months post baby