Yikes! It's not good that you're going through that many patches. If they aren't sticking to you properly they can't deliver the right amount of estrogen. If they're falling off, obviously they aren't delivering any to you at all.
There are some tricks to getting them to stick. You'll want to start by having clean hands which are dry and free of all oils, lotions and powder. The area where you are going to apply your patch should also be clear of all those things. Some of us who use the estrogen patches gently clean the area with rubbing alcohol on a cotton ball, allow it to dry, and then apply the patch. I put my new patch on before I shower rather than after as my skin is much drier before showering than it is after toweling dry. After applying the patch, hold it down firmly with the palm of your hand for several seconds to help seal and set it. If it starts to come off before it's time to change it, you can try pressing it back into place and then shoot some warm air at it using a hair dryer, being careful to keep the setting low enough that you don't hurt your skin. If you try all of those steps and still are having trouble getting it to stick, you can try covering it with a Tegaderm bandage in a size large enough to cover the patch. There are quite a few Sisters on this site who do that and have good success with that method. If all of that fails, it could be that you're just not a good candidate for the estrogen patch and would do better using a different method of delivery. You can learn more about some options in articles 10 - 13 in this link to the Hormone Article List
The patch should be changed every 3 1/2 days. I change mine on Thursday mornings and Sunday nights. I put mine on my rear as absorption is around 20% better back there versus wearing it on the abdomen. Whichever area you choose, rotate side to side, never front to back, as that can cause fluctuating hormone levels.
Weight gain when using hormone therapy isn't a given. I think it's about balance--finding the dose that gives relief without causing unwanted side effects. If there was one hormone therapy that could guarantee no weight gain, we'd all be using it.
As for testing hormone levels, it can be useful for someone who has been having trouble finding balance and whose doctor just has no idea what to try next. My experience has been that the testing isn't as good an indicator of how I'm doing as my own symptoms are. I prefer to have my hormone therapy adjusted based on my symptoms rather than by test results. Unfortunately, the levels which are considered normal are very broad and what may be normal for some women isn't necessarily normal for others.
What they test for varies--they can test all of your estrogens (estradiol, estriol and estrone) and they can also check your progesterone and testosterone levels.
Here is a link to this site's Too Much/Too Little
symptom list. You can refer to it while working with your doctor to find hormone balance. It's also helpful to keep a journal of your journey through the Hormone Jungle. Write down what your symptoms are, how often they occur and how severe they are. Also note any other medications and supplements you are using. You can share the journal with your doctor as you work together to figure out the best hormone therapy for you.
I hope this helps you!