Can hair extensions be for fine, weak hair if done correctly?

Hair Extension Experts- this is for you. I myself am a salon owner and stylist of 18 years. I am 36 and female. I was diagnosed with hypo thyroid 6 yrs. ago and had to have it removed. I have been taking synthroid and my hair from year to year is becoming thinner and more easily splits and breaks at the ends. I spend a great deal of time styling my hair and using heated, damaging stylig tools on it to make it appear thicker, etc. I have used Rogain 5% for the past five years, as well as Nioxin products and vitamins. I also have had increasing low blood pressure, and my internist is testing me and may suggest mineral steroids that will raise it. I often feel dizzy and have a very hard time getting going in the mornings. Five yrs. ago I got a very bad extension job done that nearly cost me the hair I had. It was a weft attatched to horizonal braids made up of my own hair. WAY TOO TIGHT, I had to have them removed the same night. I`m convinced if I had slept in them, which would have been impossible, I would have woke with no hair attatched. We ended up in court. I won, but oh what I lost! I cannot believe it, but I am considering trying a different method of extension, and I am very nervous about it. This is where I need some expert advice. I have been talking via the internet and telephone to different ones that say they use the great lengths method. It is supposed to be gentle, and leave the hair in good if not better condition. My biggest concern is the weight and the attatchment method not harming my hair in any way. Of course, my goal is to get some length to my own hair, and once the additions are removed not having to cut off what has been growing. Can this be done effectively on fine, fragile hair? Please help!