new to forum, needs kicking, technique suggestions

:fish2:I am new to the forums but not to swimming. I am 58, female and although I know this subject has been discussed a lot I would like to ask a few questions and get some feedback on what I do in the pool and ways to improve. I started to swim in a 25M pool 5 years ago to lose weight and get fit and have done a lot to improve myself. I also added strengthening and cardio at the gym. I have always been very slow at flutter kick and have tried suggestions such as keeping the foot pointed, keeping knees fairly straight, trying to kick from the hips. A year ago I had hip replacement surgery and when I was able to swim again I decided to try some lengths using fins to help strengthen my legs. My swim routine is now this: I swim a total of 60 mins front crawl then I swim about 30 mins using fins. I do about 20 lengths fins with a board, 10 crawl with fins and a mix with fins..crawl, on my back, with and without a board. I know my legs are stronger and my endurance greatly improved. At the gym I do 15 to 30 mins on cardio such as the bike or elliptical trainer, leg press, leg curls and extensions and have increased the weights over the past few months, as well as a variety of arm and shoulder work, since I started back 9 months ago. HOWEVER....now I litteraly stand still if I try to kick without fins. Although I know my muscles are stronger I am kicking worse. Exactly which muscles are used to have a good flutter kick and what exersises in the gym can I do to improve them? Also can anyone recommend a book or DVD that will give clear help on stroke improvement. Sometimes I find a written description of how to swim crawl not clear enough. Thanks.