Yeah, some chins are like that, you may need to make the hay more appealing. Are you feeding her the same hay she was eating before? Chins can be very picky about their hay, if they don't like it they wont eat it. If there is nothing wrong with the hay (smells sweet and fresh, not, old, moldy, or dusty) you can try mixing different kinds of hay together, you can even add a bit of alfalfa to make it tastier. Although timothy is the most balanced hay any grass hay (meadow, orchard, brome, etc) is good if you chin will eat it. Chins also do have preferences when it comes to brand sometimes, maybe due to were it's grown or how long it's been in storage, but apparently timothy hay is not all the same to a chin. I normally give my chins at least two different kinds of hay (timothy and something else), in addition to a couple alfalfa cubes a week. Another benefit of different hay is that the chin chews each differently, which can help grind the teeth down more evenly.
One example of hay and herbal mix that seems to get rave reviews is
Furry Kingdom's foraging hay, it seems to sell out very quickly, but should help you get an idea of making a hay mix. She also sells just the hay topper, so you could just mix that into your own hay.
You only say she doesn't eat much hay, but if she tosses a lot you can try giving her smaller amounts at a time. I only normally put one or two handfuls in the cage at a time, otherwise my guys tend to think it's a fun thing to play with and toss it all over the cage. :facepalm: If the hay is not soiled or on the floor you don't need to worry about changing it. Changing it all can devalue the hay, basically giving the chin the idea that they don't have to eat it, new hay will be proved later so I can play with this hay.
To give you a better idea of 70-75% of her diet being hay, she should be eating at least a handful a day, or a pile about the size of her. You are doing right by only giving 2 tb of pellets a day, so long as it's a pellet only food (if it's a treat filled food it's best to switch to a pellet only). The hay is really the primary food, with the pellets giving them nutrients the hay may be lacking. Pellets don't wear down the molars, they are too soft, and don't have enough fiber, specifically the long strand fiber since the hay in the pellets is finely chopped up.