She seems to have lost her vocabulary. She plays by herself, doesn't seem interested in playing with adults or other children. Her advancement seems rather slow. She still isn't eating well, and nurses as much for comfort as for food. (She will not drink milk in any form, including expressed mother's milk, though she does sometimes eat cheese.) She goes to bed late (typically 10:30 to 11:30pm), and gets up early (if not at 3am to nurse, she'll often get up between 6 and 7am). And she won't go to sleep without a parent present.
A lot of parents insist that she'll learn to talk in her own time, and seem to feel that we're overly concerned. The thing is, late talkers usually advance in other areas; she doesn't seem to be advancing at all. So we took her to a child psychologist who ran some tests on her and said that Mariel tests at a 14-month-old level, and she is very concerned.
Yes, we had her hearing checked. Even had we not, it's obvious that she can hear perfectly well, as she sometimes reacts to verbal messages that are not accompanied by visual cues. Those times she doesn't, she's obviously just ignoring us.
An interesting side-note: She doesn't seem susceptible to over-stimulation. Take her to a party with lots of people and noise, bring her home, and she goes to sleep at the usual time (late) with no apparent side effects (most kids throw screaming fits, sleep fitfully, wake up in the middle of the night and throw screaming fits, etc.).
For the last six months Mariel has been taking speech therapy, occupational therapy, and sensory integration therapy. Some of her therapists have tentatively diagnosed her as having some form of dispraxia, or something very similar. Again, she's too young to make a positive diagnosis, but she does have a number of significant symptoms.
She reacts badly to certain kinds of sensory input -- essentially, she doesn't like stuff that feels gloppy. She went nuts when they tried to make her play with some pudding. Some foods she'll eat, but be very careful not to let them touch her lips. She prefers crunchy foods. She doesn't like plush dolls, much preferring plain cloth dolls.
However, she has improved in the last six months. For one thing, she'll sometimes drink milk, but usually only if it has chocolate. For instance, she drank a significant part of my chocolate milkshake recently (a real milkshake at a real restaurant, not a McDonald's "shake").
She's starting to regain some of her lost vocabulary, and of course is adding to it. She still goes to bed late and wakes up early, driving her parents crazy. Well, crazier.
Her sensory integration therapist discovered that Mariel is very susceptible to sensory overload; it's not obvious at first, because as soon as she goes into overload she sort of shuts down. She becomes very detached, and just ignores almost everything around her. (This explains the lack of reaction to over-stimulation, I believe.)