Honestly, DogFiesta.com is doing very well. If you are looking for something that can work for dogs only … but for ALL aspects of dogs … "Fiesta" is vague enough to include everything, but fun and familiar to an American English-speaking audience – which is important. And "dog" is precisely the word you want to target; so it's crucial to have it in the domain name. If you want to use an alternative, I suggest that the second word begin with an "s". In this way, the domain will contain both "dog" and "dogs" and will benefit from both traffic flows. Maybe DogSource. But the second word must be a common word – something catchy and unforgettable. DogSource has a disadvantage because "source" is a rather abstract term, difficult to visualize. DogFiesta, on the other hand, claims a logo that will help people remember your website. This logo – without a doubt – should be an image of a real dog wearing one of these conical party hats.
P.S. Stay with the .com. There are many options available in this extension. Since you have already registered DogFiesta, I will not continue to search unless you want to increase your budget. If you had a bigger budget and more time, you could search for a different domain from the .com variety with a strong second word starting with "s" – an instantly memorable word, like "fiesta".