My daughter also potty-trained at 2 years old. We were so thrilled not to have to deal with diapers all day! However, it is normal for kids to have nighttime wetness until 5 or 6 years old - their bodies are just not physically mature enough to control the bladder until then.
For us, we did not even mention trying to stay dry at night. We called the pullups "sleeping undies" and just kept using them until she REFUSED to wear them anymore. When that happened, we made a deal with her. If she could keep her sleeping undies dry for ONE WEEK (we made a sticker chart), then she could try sleeping in regular undies. It worked, but note that this was initiated by HER, not us. We then made sure her waterproof pads were in good condition and dealt with the occasional accident with as much gentleness and understanding as we could. We also "double make" the bed - waterproof pad, sheets, blanket, ANOTHER waterproof pad, sheets, blanket, and comforter. This way, in the middle of the night, we just remove the top layers, and pop her back in bed.
One thing I would say is, don't try to "train" her at night. She'll be dry when her body is ready. Pushing things along could cause setbacks in other areas of development. It's just not worth it. One thing you CAN do is limit the nightime fluids. At nearly 3, a sip of water at night is not necessary unless she's sick.
And another note - once she IS dry at night, then a nighttime accident is often an early symptom of a cold.
And, just in case you're interested, my daughter was day-time dry (no accidents at all) around 25 months and nighttime dry just before her 3rd birthday. And yes, she still does have accidents at 4 years old!
Good luck,
K.