Pulling her out of preschool may not have worked in your favour, since it threw off what she was used to, and made her more cranky in all likliehood.
Are you able to get out and do "special" things with her, just the two of you? different ages, but I did that with my oldest when her sister arrived when she was 19 months. We STILL have "Mommy Time" every so often so she knows she'll have my full attention at some point. We all need that after all.
Sounds like she just needs a little extra bit of reinforcement from mommy...
Hope things are better now. It's hard enough with a new one around.