Have you ever thought of yoga, meditation, visualization, hypnotism? Nor harm in doing as an adjunct therapy.It is claimed in youga, posture's efficacy increases if you do mulbandh(Contract root chakrs). Similarly with all work out if root chakra is contracted , it may help too make your work out effective.That is just my ides. For knowing about mulbandh Google the word. It may look quire and inelagant, still try to understand it.They also knon as Bandhas.
You say you have kept logs, have you kept the same excercise routines too? Try switching every four weeks, and do both CV and weight training, for four weeks of CV try mixing running, rowing, cycling what ever but train smarter so a five min warm up then go balls out for one minute then slow right down for one min, alternate until 30 minutes are done then cool down, as your a female and I'm assuming you want a times rather than bulky physique, do weights but high reps and low weight to failure but probably no more than 3 of the same excercise and alternate body part. After four weeks change the plan maybe change your CV of choice and incorporate a swim rather than weights to keep flexibility then after a week get back into smashing the four week plan your body will burn calories keeping up. Also as previously stated measure body parts, I was close to giving up when it looked like I had only lost 7kg, but on looking at the tape arms and chest bigger, and I can fit into a pair of jeans I bought as an incentive earlier in the year. Hope this helps and not too confusing.
Not to sure about the diet pill recommendation... most of those deal with water weight - except the real prescription things and those aren't exactly safe either. What does your doctor say? Also, even if your weight stays the same, have your measurements shrunk???? Think about that.
As for healthy eating... I'm not a big fan of nutritionists, but they do know something. Use the Diet Diary here, track your carbs/fat/protein. I've had good luck with low carb, low fat high protein, but that probably doesn't work for everyone. Ask your trainer what he or she uses - they're usually pretty conscious of what they eat. Tracking what you eat also keeps down the munching (that's my problem).
Worst case... read read read.... there are lots of books on healthy eating. Look for one that is middle of the road. Or try Weight Watchers - not my deal, but it really worked for a friend - again they have lots of informaiton on healthy eating and they'll share.
I have tried them on and off but I have never stayed on them for any long period of time. I guess it wouldn't hurt to try!
Maybe you should try some diet pills. People use diet pills whenever they hit a plateau just like you, and it's only so that you can keep on losing weight.