{I'm sorry it's been frustrating for you.}
I'm sure you'll get lots of suggestions, but the first one I'd make is to look at your calorie intake. I know there is some feeling in the LC community that calories don't matter very much, just eat 'until you feel satisfied' etc., but many of us have noticed that calories make a difference.
Sometimes the problem is not enough food and your body goes into starvation mode, which is the slowing down of your metabolism to cope with less fuel. Others times, we're just eating too much to make a consistent calorie deficit.
A million things could be affecting while you're stalled ... stress, hormones, medication, sleep disturbance, sugar alcohols, psychological issues around crossing the 300 barrier, the moon in Gemini ...
Whatever it is ...
hang on to that rope!
I've been here more than a year now and keep reading stories of people who hung on through periods of very little loss ... and they're the folks who eventually have made the most progress. Don't give up! You're going to be one of those people someday.
{Good Luck!}
PS - Here is a
link to a forum article on Stalls. It has some great suggestions.