For those of you who finally had weight loss success

Hello everyone. I am a 28 year old female, I am 5'10" and currently weigh 184-ish pounds. My weight has been a struggle my whole life. I really do not overeat. I also eat pretty healthy. I eat organic and I am aware of my carbohydrate and fat consumption. I also count my calories. I usually eat inbetween 1200-1300 on a regular basis...and on special days (occasionally/weekends) I will end up around 1600-2000. I do not feel like I am starving. I get full very eaily!

However, all of my life I always have an extra layer of fat on me I cannot shed. I cannot lose weight...or lose inches. If I do...it is extremely difficult and will usually gain it back plus some.
I have tried everything!
Calorie counting... I've tried everything from 2000 calories..1800...1600..1400...everything. I've tried all ranges. No success!
Atkins diet
South beach diet
Gluten/dairy free (with success...lost 8 pounds! but then it stopped and started coming back again)
Weight training.
exercising an hour, 6 days a week.
I read that may be too much, so I cut it to 30 minutes a day, 6 days a week.
I then read that may be too little...upped it to 1.5 hrs a day, 6 days a week.

As the years go on, I find it increasingly difficult. I was gaining at an alarming rate (thus..why I am eating the mimimum...1200 calories per day) and now I am maintaining.
I have had my thyroid checked 4 times (always comes back healthy, which is good)...and my family is concerned for me. I feel very down about the fact that I feel like I have no control over this and I don't know what the deal is?

I've been maintaining at 184 for months now...I hit 192 this summer and became really depressed about it because I was trying so hard. I'm scared to go out to eat sometimes! It seems like when I eat anything extra (around 1800-2000) I gain weight like mad!

I am seeing a new doctor and tested my blood for various things. He said I am very healthy except I have low B12 and Iron. I asked if this could be causing my problems and he said yes! So I have been taking those supplements for a month and a half now...with no results at all!

My question is for those who had a similar problem...had a healthy thyroid...gained weight very easily....ate healthy...exercised...couldn't lose weight or inches. For those of you who found out what the deal is? Was there something else wrong that caused this? Was there a vitamin or supplement? Was there a food intolerance? Was there a trick that just seemed to work for you?

I'm at my wits end...I just don't know what to do anymore, besides continuing eating only 1200-1300 calories a day just to maintain my high weight.

Help? Advice?