I can offer an idea on why you haven't been offered OB. Since OB is such a highly specialized unit and since it takes so long and such a great investment in the nurse to end up with a first rate L&D nurse, the hospitals can be expected to look for experience first. I recently completed the transfer from med-surg (with 4 years experience, all at the same facility) to our LDRP OB unit. I started by floating (yep, the nasty F-word of nursing) and caring for mother/baby and gynies, helping out with L&D as time allowed and just doing the general grunt work; answering call lights, doing admissions, starting IVs, pulling foleys, etc. When I was sure it was something I wanted to do full-time, I applied. The process wasn't as simple as I'm going to describe it, but in the interests of not losing your interest with a long post... I got the transfer. I was a known quantity in the hospital, the team with which I am now orienting knew me and I know that I'm compatible with them, and I have a head start over a new hire because I'm already familiar with all the non-unit-specific workings of the facility. Its turning out to be a fairly smooth transition.
My advice? If an offer of OB doesn't come your way using the others' suggestions, accept a med-surg position at the hospital with the OB unit of your choice with the written proviso that the hospital will provide you with classes (fetal monitoring, NALS, or whatever its called now, etc) and "first shot" at an opening in OB after a decent period of time of continuous employment, perhaps 6 months to a year. (This is part of my story that I didn't bore you with that a competing hospital offered me & I came near to accepting.) It may not be ideal as far as time is concerned, but it gets you in the door and, at least here, the pay is the same so money isn't a factor. Just thought I'd throw out the idea for another route to take. I wish you the best.