Advice needed, please! Mother Cat is starting to be more aggressive with over-8 week-old kittens

I have a couple of other threads in this forum and one in ferals about my rescued stray and her kittens but felt this needed to be a new one so it wouldn't be overlooked because I'm not sure what to do.

Today I noticed that Henryetta was starting to become less tolerant of her kittens' behavior, especially during playtime. She now wants to play but  was kind of biting at them and kicking at them with her back feet when they started jumping at her and vying for toys.  I wondered if this was because I was playing with her and the kittens and they were kind of "sharing" the toys - ribbon and stuffed mouse.  I had to clap my hands to stop things. Is she over-stimulated after being so tied-down to caring for them or is she wanting away from them or wanting them gone?  Other than a few days when they were all in the house and confined to different rooms after she was spayed and not together in the storage room, they've not been apart.  She's also been a little touchy with me lately.  Is it time to bring her into the house where she eventually (and hopefully) will live with my resident cat, if they adjust to each other, and leave the kittens on their own with less supervision in the storage room until I can have them adopted which I know now will be several weeks from now?

The exact answer is not easy. There may be several partly different possibilities.

1.  The usual starting of rejection, the starting of the separation process.

  1b)  she is spayed, so it cant be the subvariation she is rejecting them now to prepare for the new litter.

2.  She recognizes they are bigger now, and thus, they  manage also a more rough treatment  not being as fragile any longer.   Its OK now to call a spade for a spade!

3.   It hurts her somewhere.  Cats in pain dont have the same patience as usual, and thus, tend to give lessen either they are necessary or not.

There may be more possibilities, these are what Im thinking on at this moment.

Good luck!

Thank you for suggesting the possibilities.  The storage room gets very warm and stuffy even with the addition of the screen doors so she may get fussy due to the heat and closeness. It's very warm and humid where I live at this time of the year. I've managed to get one of the windows opened so hopefully there will be better airflow through the screen. 

I'm beginning to think the combination of the heat and over-stimulation during playtime contributed to her more aggressive stance with the kittens. She's calmed down now and today was allowing them to land on her, jump at her face and play with her tail without grabbing them and seeming to bite at them. She was also licking them as they passed and supervising them verbally when they were getting out of control racing around the room and leaping up on the window ledge.