Lump next to kittens throat

My little 8 month old girl had a lump seemingly pop up on the right side of her throat under her jaw last week. It doesn't hurt to touch and she has NO other symptoms, still playing, eating, not loosing weight etc. She has already been taken to the vet by my partner, so I don't know EXACTLY what they said, but basically it's seems it's just a nodule or fat store, like how humans have those under the skin pimples, so it's no issue. Vet said we can do a blood test just to be sure but my partner had to go to work so he didn't want to wait around for it to be set up (which is super annoying cause it would have been over and done with already!).

So my question is to blood test or not to blood test? I just hate putting her through the stress of taking her to the vet twice in one week, she gets so so scared. As I said though if my partner just had of done it while he was there it would have been great. But basically she is probably fine but it would be peace of mind for me but is stressing her our worth my peace of mind?

I would take her for the test but you might be able to reduce her fear by spraying something like Feliway spray in the carrier. Also keep the carrier covered - that helps as well.  I completely know what you mean about not wanting to stress your girl out but it really is better to be sure about these things. And peace of mind is invaluable.