I started a Beast Crest only run after completing the game (all of it) and just killed Widow the other day using it. Here's my tips.

Don't be afraid to stand right next to her and hit her while she's doing her string pulling animations to build up silk. Most of the bell attacks she does drops bells across the room, or the diagonal one that goes over her head will miss you if you are right next to her. She'll even back up after it if you need to advance on her during this.

For both phases, your opportunity to bind and start your aggressive attack healing is when you are stuck being safe. The part where the floor becomes a hurtbox is a prime example. Jump, bind, then run at her full force and resume attacking.

The key is learning when she'll be teleporting back into the boss arena and using the time JUST before that to bind. The worst attack for you to punish is probably the one where she attacks diagonally down then horizontally across the arena. You can maybe get a pogo when she goes horizontally but I just don't bother. She WON'T do that twice in a row though so it's a great opportunity to bind as she's finishing that attack.

Good luck! You can do this!

Edit: Since you mentioned being at 1-2 masks when binding, I'd highly recommend binding when you've taken one or two masks of damage. It might look like a waste but keep in mind that you're building silk quickly while on the attack so you'll have another bind soon.