Awww.. That can be frustrating, I’m sure.
First, I’ll ask if you can put a litter box at the foot of your bed since Tulip seems to have taken a shine to that place? If you can, litter training isn’t too hard. At the top of BB, under Bunny info, there are some great tips. But if she’s chosen this place, sometimes it’s as easy as putting the litter box there, with litter, some hay (bunnies love to eat and poo at the same time) and some times a little enticing treat like a leafy green to make them jump in.
If you don’t want her peeing/pooing at the foot of your bed (understandable) you may have to show her where to go. When you see her get into position or lift the tail, you may want to relocate her. I’m sure someone on here has better advice than that, sorry. For my bun, she kept trying to pee next to the litter box, so finally I caught her trying to do that, picked her up really quickly and deposited her in the box and she didn’t even really miss a beat, went potty and she was trained after that!