Oh, I can TOTALLY relate to what you are saying. I remember feeling this way EXACTLY. My son is now 2 1/2, but I remember just around 12-15 months going through the exact same thing. First, I think you are doing great! Sounds like you are giving her development so much thought and attention! By just the fact that you are so concerned, it is probably a good indicator of how great a job you are doing! It's so hard to know, isn't it? You read all of these articles and books, and there is so much advice out there, but I remember feeling like, "Someone come over here and tell me what to do and what to buy at the store!"
With the food, sounds like she's eating well and just about everything all kids her age eat! I know it's hard to try new things when you just want your kid to eat, so you feed them what you know they like, but then they get bored, and you get bored and worried about nutrition, etc.
I say, simplify. Go back to basics; banana, avocado -- hell, my son ate gerber sweet potato puree and carrot puree until we was 22 months -- I bet he would still eat it if I bought it for him! Tomatoes, mashed potato with lots of milk and butter, if she eats pasta you have the whole tomato sauce, mac and cheese, butter noodle trifecta. You could try little bits of meat, sausage, garden burgers, if she eats lentils, she might go for other beans. Fish sticks, if she eats chicken nuggets. Try all kinds of fruit, pears were a real hit in my house.
If you have friends in Cali that have kids, one thing I did when I was feeling like we were in a toddler food rut: I emailed all my friends with kids and asked them to send me a list of everything their kids ate. I got a few ideas, but the most important thing I learned was that when I reached out to other moms, I found out my son was eating practically the same thing as everyone else.
As for activities, maybe check out some second hand baby stores in the area and get some books and new cheap toys. At that age, there's nothing that spices up a baby's home life like some new gizmos. Also, rotate the toys for variety. If you take some away for a while, it will be like a whole new toy in a week or two!
As for books, my kid LOVES to read. I think it really depends on the kid, but we read a lot to him around that time.
Also, check out Community centers. I found this link:
http://portorchard.net/organizations.htm
there's a mom's club listed there and a rec center -- looks like all sorts of moms stuff. I know in Seattle and Burien they have toddler gyms at the community centers, but I'm not sure what's available where you live. Toddler programs are a great way to get out of the house and get her interacting!
Interaction with other kids is great, but, in my personal opinion, I think it's a little overrated these days. As corny as it sounds, all the learning at this stage of the game comes from you. As long as you are talking, imitating her sounds and words and engaging her, you are doing awesome.
This is also a helpful resource:
http://moms.meetup.com/
Could it be that you are a little bored? Adjusting to your new surroundings? Maybe some time away, checking out Craig's list and looking for a babysitting swap or some part-time childcare so you can take a breather and recharge? Looking back, I feel like I was so involved and thinking about it 24 hours a day that taking a step back made me appreciate all my kid really did learn. Sorry to be so long winded, but I really wish someone would have said all this stuff to me. Good luck!