You should ask yourself if you can finish the first node without recharging or if you want the next node as well. This really helped me a lot after tons of math. Because hear me out, even if you have a monthly card, even if you don't, there are still 9 days left which means 9 free pulls. That's 60 for now with the pulls you've already made. What you're left with is 20 pulls and that's 600 diamonds.

Here are two cases:

1. You have a monthly card already:

9 x 140 = 1260 diamonds Postcards: let's say 65 diamonds average, that's 585 diamonds.

Plus what you get back from pulls, that's like another 100 diamonds back if you're lucky and don't get gold or stamina

That would be 1945 diamonds without the competition reward, arena, chapters that you may not have completed yet, free suits you didn't crafted until now and house tea party.

1. You don't have a monthly card:

9 x 85 = 765 diamonds Postcards: 585 [again, it depends on your luck. This is just an approximate] 100 back from the event 1450 diamonds

If you have gold, save it and buy an item from the Shopping suit. Preferably the hair as its the first item. Then decompose it again and again and open those boxes 100 at a time because it's easier. I got 300 diamonds yesterday from those and they are always a lifesaver when I don't have diamonds and I also can't recharge.

Either way, good luck and I hope you get what you want :D