Old cat likes new kitten, but is a different cat now :/

I have a 1.5 year old female siamese K that i've had for over a year now. She's the sweetest most affectionate cat, is super social, is always on my lap, kneading me, purring and wanting attention from me, and since she's a siamese, always walking around meowing and talking to me... I couldn't go to the bathroom or shower without her wanting to be next to me. I work from home so we are inseparable. However, I am getting another job where I wont be working from home and I thought it wasn't fair of me to leave her home alone for 12+ hours a day.. so a month ago I got a 4 month old male kitten, B. I did all the steps to introduce them and it worked! they have been getting a long great, they chase each other and play and play-fight, eat together, nap together and groom each other, it's very cute.

However, that's starting to cool off a bit. They still play but she will sometimes growl at him and doesnt like it. In the 1 month he's been here, he's already grown to be larger than her and since he's still a kitten, can be pretty boisterous and rough. But also, K is really different. She's no longer the very social and affectionate cat I once had. When she's not playing with B, she's not doing much else and she no longer tries to be super affectionate with me. She just sort of sits or lays on the ground and watches everything. She used to run around crazy for toys and loved the wand toy but now barely wants to play with it. 

Is she still just needing to get used to B? Or has the introduction of a new kitten changed my once amazing cat's personality? 

Thanks

What's the dynamic between you and the new kitten?

How is K behaving when he's around or when he's not?

I am curious as to what others would say about this.

Is it because she's emotionally drained from having to deal with another cat?

Is it adjusting?

And

K is still an amazing cat. All that's happened is that, now she's got B around, she's less desperate for attention.

The change in play habits will be because she's running some of her energy off with B, and also a sign that she's growing up. Sometimes, as cats mature into full adults (as opposedto teenagers) their play style changes. Instead of wasting energy running all over, they'll watch and wait for the perfect moment to pounce. In the wild, it's all about refining hunting techniques so that as little energy as possible is used up in the hunt, and sometimes these instincts get carried over into domesticated cats.

I suspect her growling at B is her putting him in his place. As he gets bigger, stronger and heavier he may simply be overstepping the mark in her eyes. So long as it doesn't escalate it's nothing to worry about. Many cats who live together will have occasional spats - just like we'll sometimes argue with our partners or family members.

Thanks for the replies. 

The dynamic between me and the new kitten is good, he is very playful and affectionate and I do give him a lot of attention. I have been keeping them separated for different parts of the day to see how K reacts, and for the first time yesterday in a long time she actually started purring and kneading me and being affectionate, but it took a lot of effort on my part to get her to give in! But she's never acted that way when he's around.

I got the new kitten to keep her company and I just hope that she's still adjusting and not getting depressed over the new addition. 

She doesn't sound depressed at all to me. It's a good idea to make sure she still gets some alone time with you though - all my animals really appreciate one to one attention, even though they're happily integrated and get on well together.