Some of your 'shortcuts' are not good ideas. Definitely start with cold water. Definitely bring up the temp slowly. Definitely do not boil. Do add aromatics upfront to the broth, but remove them as they get mushy so they don't cloud it.
Standard ratio for beef broth would be: 8 pounds of bones to 6 quarts of water to 1 pound of veggies (onion, leek, carrot) to one 'boquet garni', essentially garlic, rosemary, anise flavoring for pho, and bay leaf, plus whatever else I forgot.
If you have 'pond water', which I interpret as thin-tasting, you probably put too much water in the second time -- this is fixable by slowly evaporating out the water until it gets to a good texture. If you skimmed properly, it will be clear as you do this. I will typically strain through a kitchen towel or cheesecloth as the liquid evaporates down.
I'm guessing you put in like a gallon of water, so you had like three or four times too much water.
As a warning which you probably already know, you are not going to be able to duplicate your local pho joint's broth -- the broth recipe is the thing for pho makers, and they probably have a bunch of tricks they use, including using a neverending supply of yesterdays pho, that you won't be able to do at home. That said, you should be able to get a good beef broth if you follow some basic rules for making stock.
Classification and use of Stocks vs. Broth:
Broths are the result of cooking meat, not just bones. They're generally the result of preparing another item and usually not prepared specifically on their own. The juices poured off from a roasted turkey (after being degreased) would be considered broth. Whole chickens being poached for another preparation would create broth.
Stocks are made from just the bones. They are prepared specifically for use in other recipes (sauces, soups, stews, rice, etc.) Stocks are never salted in their preparation or the finished dish will most likely end up too salty due to reduction that will take place upon further cooking. Note that homemade stock will be often a bit more broth-like than restaurant/commercial stocks, since it's really hard to get all the meat off the bones.
Stocks are usually simmered for a very long time (4-6 hours for chicken & 8-12 for veal/beef) to extract maximum flavor and gelatin from the bones.
Broths aren't usually cooked nearly as long due to the fact that cooking the meat for extended periods (even chicken surrounded by the liquid) will result in tough, flavorless meat.
Consomme: a fortified and clarified stock. The stock is fortified in flavor by the addition of a "raft" which is a combination of lean ground meat (appropriate to the type of stock being used) with brunoise (1/16 inch) mirepoix (carrots, onions, celery), and egg whites. The raft mixture is stirred into the cold stock and as it gently heats, the proteins coagulate forming a "raft" on top of the stock. A small hole is poked in the center (if one hasn't already formed) and as the stock bubbles through the hole it leaches back through the ground meat/egg white raft which filters out impurities to clarify the stock and fortify it with flavor.
Bouillon: French word for broth.
Court Bouillon: sometimes called a "short broth". A poaching liquid usually used for fish that is usually comprised of water, acid (lemon juice, vinegar, wine), parsley stems, bay leaves, peppercorns, and some salt.
When to use Stock vs. Broth:
Use stock when a sauce is to be reduced significantly or when clarity of the final result is preferred.
Broths can be substituted for stock when the body of the liquid or clarity isn't important, and when the liquid will be thickened by addition of a starch.
Best Answer
No, and there are many reasons why what you are doing is what you should be doing!
Well, I can find many sources that advise you to add the vegetables towards the end of the cooking time. For example, from The Kitchn:
And it makes total sense. At my household, we make bone & vegetable soup about once a week, and are pretty familiar with the timing of each ingredient. We usually just put in the "soupable" vegetables that are lying around in the house, so the recipe is always changing.
Here is our rule of thumb as to which sort of ingredients go into the pot before others, though other household may vary:
Bone and meat.
Medicinal aromatic ingredients *(like dried shiitake mushrooms) and salt.
Root vegetables (like carrots) and vegetable stalks (like cauliflower stems).
Leafy greens (like lettuce) and herbs.