Hello. Thank you for coming to JustAnswer with your question, and welcome.
Please don't stop taking your thyroid hormone, you are making progress with this as evidenced by your increased energy and less feelings of depression. The thyroid hormone is not causing you to gain weight.
Your other symptoms are most likely caused by being overweight, so this is what you need to work on (and I think you already know that).
Talk to your endocrinologist about the testosterone. If you need testosterone, this will definitely help you---with thinning hair, and building muscle instead of fat (plus muscle needs calories, so you will be using more calories even when not exercising).
To lose weight, you need to become a specialist in food and diet, so that you know exactly how much you are consuming in calories. Do not forget about any beverages you are drinking that may be high in calories. By consuming 500 calories per day less than what you need, you will lose weight. And you need to keep exercising to accomplish this also.
Here is a link to a site that will help you assess your current status. As well as give you some guidelines to get you started. Aim for a Healthy Weight
You need to start by simply doing a food diary. Write down everything you eat, and the amounts.
Then learn about portions and calories. A good site for helping you with determining calorie content (plus fat, protein and carbs) in foods is Calorie King which has a free food look-up for nutritional information.
It does take effort, but it is well worth the work when you feel and look better. I have seen people who exercise daily, and cut and count their calories lose up to 50 pounds within 3 months. But you have to be persistent.
Just don't stop your thyroid. Your body will not be able to regain a normal metabolism so that you can eventually lose weight without it.
Sorry for the delay, just saw your post when I signed on this morning.
Thyroid hormone (your own or synthetic) works to regulate metabolism in every cell in your body. This means the hormone controls the conversion of oxygen and calories to energy so that your cells can use it. This conversion is "metabolism".
Without this conversion, your cells cannot use the oxygen and calories. So, with the calories running around with nothing to do---your body will store them as fat. Not to mention that your cells cannot do whatever their particular job is---this is what causes the symptoms of hypothyroidism.
Thyroid medication does not cause weight gain. There most likely are other things going on that could cause this. Most likely scenario (at least for most people): to gain 14 lbs in 3 months you would have to eat 540 calories more per day than the body needs. That isn't very much (a little here, a little there). We very often just do not pay attention to how many calories we ingest.
The endocrine system is very complex. If your doctor feels you are getting too much thyroid hormone based on test results and symptoms you have (too much would cause palpitations, poor sleeping, jitters, etc), then he would reduce the dose.
Many people put too much emphasis on weight loss and gain when taking a thyroid supplement. Usually, for someone with mild hypothyroidism, which yours may have been, based on your TSH, any weight gain is caused by fluid retention. This fluid retention is lost when you start taking thyroid, so you get some initial weight loss. More severe hypothyroidism, or milder forms left untreated, over time will cause actual fat weight gain because the body cannot use the calories ingested for energy (so you have symptoms of fatigue, sleeping a lot, weight gain without much food intake, etc).
Here is a link that explains thyroid function, and some of the complexities of diagnosing what the actual problem is and treating it: How Your Thyroid Works. There are also links on this page for more information about thyroid problems, tests, treatment.
Whatever you decide, you should discuss with your doctor. Perhaps you do not really have hypothyroidism. Your problem might be something else. A TSH of 4.5 is a high normal, or slightly higher than normal (depending on your own labs ranges, of course)
It is very natural for older people to gain weight in the 5th and 6th decades of life. This is a time when everything starts to slow down, and we often don't use up as much energy as we used to. Exercise and controlling your diet are the first steps to helping yourself. And exercise is the best way to boost energy levels.
So, while you are working with your doctor, take a serious look at your diet. Keep a food diary to see where you can make some healthy changes. Also, if you are continuing to take thyroid hormone, make sure to take it first thing in the morning on an empty stomach about an hour before eating. And do not take any calcium containing foods or supplements for 2 to 3 hours afterward, as calcium can block absorption of the thyroid.