Maybe a stupid question...

So, my college has a 'Bug Zoo' which is a collection of insects and arthropods that we use for outreaches and education. I'm taking care of the collection this summer, and one of our critters is a juvie Oklahoma Brown Tarantula (or at least, that's what I'm told, but it was a guess). I was told to feed her baby cockroaches from our Madagascar hissing cockroach colony, but every time I've tried she's refused or run away. I was going to buy crickets from a local store, but I was wondering if there was something more appropriate for a tarantula, or if I should just keep with the roaches (maybe I'm picking to small of babies? They are about half a pinkie fingernail I'd guess)

https://lh3.googleusercontent.com/-h...617_161256.jpg<--- Gratuitous picture of me holding our T because I think she's the cutest darn thing... I've been calling her Charlotte, but she doesn't really have a name haha

I'm not super worried- I did a little reading and they said that it's not weird for them to go off feed for a bit, and her butt hasn't shrunk so I don't think it's getting to dangerous levels (it's been about three weekish). Maybe she's about to molt? IDK D:

It is quite a possibility she is going to molt. All of our Ts stop eating about a week or so before they molt & wont eat for a few days afterwards.
Her size is good, if not a little overfed. All mine look plump like her & a friend who breeds Ts said mine are "fat".
It just may be that she is not hungry. She will eat when she gets hungry.

Yeah, that's about what I figured (she'll eat when she's hungry) and I wasn't super worried- just more reassurance I'm not feeding her the wrong prey haha.
They said they've been feeding her a baby roach about every two weeks (or whenever she eats), is that too much then if she looks a little overfed?

No, not too much, I'm not positive on this, but Ts normally eat when they are hungry & she appeared well fed & healthy. Ours eat 3-5 crickets every 3-4 days, if they still have crickets at next feeding then we skip feeding.