Hi Stoops
Not a teacher - just a Mum - but first off it doesn't sound like your DD is doing too badly. Have a look at the MN info on progressing through NC Levels here: www.mumsnet.com/learning/assessment/progress-through-national-curriculum-levels
Scroll down and you'll see that on the second table - the expected notional achievement for a child is 2A/3C by the END of Y3.
So in fact your DD is doing slightly better than expected - as she's 3C or 3B right now and it's only 1/2 way through Y3.
Another little wrinkle is that schools seem very keen to achieve NC L3 for KS1 SATs and then there does seem to be a roll back of these scores. Several reasons:
Grade inflation (frequent if infant & junior schools are separate - just have a gander at the 'staffroom' bit of the education MN)
Transition Dip - the work does change between infants and juniors - it's more formal, more is expected of the students and things get a bit tougher - so initially there can be a plateau/ period of adjustment (again see MN blurb on this: www.mumsnet.com/learning/assessment/transition-dip
Gaming of the system: So the score at KS1 will just be 3 on the SATs. Some schools just start kids off at 3C, regardless if they're working higher. It does mean less pressure to achieve 1-2 sub-levels during the year - easier to show you're on target to Senior Management as a teacher.
OK - can you make a call on the 11+ at this point? To be honest it's hard to say really.
DD1 scored NC L1 across the board at end of KS1 SATs and was NC L2C by this point. My DD1 (now Y6) wanted to sit the 11+ so we agreed. She doesn't look to have scored high enough for entry to our highly selective but free grammar schools here (it's something like 1 in 7 succeed) - but I actually think going for the 11+ was a good thing. I wanted my daughter to leave primary as a strong student and that helps her regardless of whether on the day she passes the 11+ or not.
Like you - we opted to move into a good catchment over last summer - so I did have the security of knowing if DD1 didn't pass we had a very good alternative. But preparing for the 11+ meant radically improving the quality of her reading material, pushing beyond just multiplication/ division (really inverse multiplication) facts and starting to do proper maths work (long division/ multiplication, solving simple algebraic equations, working out area or circumference, converting cm to m, etc...).
We tackled it in three ways:
using recommended reading lists for the 11+ to improve quality of fiction she was reading
using an on-line maths tutorial (our school is very lazy about any homework - so this was our way to help DD1 catch up post KS1 SATs (she scored NC L1 across the board)
using 11+ prep books - like bond (especially 10 minute books)/ letts/ etc...
I never expected her to definitely pass. I knew we had a mountain to climb. But boy she came jolly close - just 10 points shy of the predicted cut off this year (we'll know for sure in early March). It was just me, mathsfactor (an on-line maths tutorial we've been using since late Y2) and workbooks (often borrowed from friends). Given all the givens with her incredibly poor start during KS1 - I'm over the moon and incredibly proud of her. Moreover, I know that she's set to do very well on KS2 SATs which will feed into her new senior school and their decisions on which 'form' to place her in.
So we feel she's leaving primary school in a very good place and that preparing for the 11+ raised the quality of her comprehension, reading skills, vocabulary & maths skills. She put in a lot of extra work over Y5, often knowing (and feeling a bit glum about it) that her friends were doing nothing at all, just playing endless video games (we had no homework from the school for 4 months). So from our perspective we're relaxed, pleased with what she's achieved and looking forward to her starting in a school that looks to be interested in academic achievement (unlike her primary).
So don't be so worried about whether your DC is academic or not at this point - gosh it's ever so early to really be sure. But do think about what preparing for something like the 11+ - aiming high in other words - might mean long term.
HTH