How long does it take for my female betta to reach full size?

It depends on which variety/species of betta she is. Also, a photo would help. Honestly, as long as she is eating and acting fine I would not be too worried about her overall size. If you have her in a very small tank/bowl then you may have stunted her growth inadvertently. This article may help you. https://pets.thenest.com/make-bettas-grow-bigger-3705.html If you have more questions please feel free to post again.

The best guess would be an adult. Unless you know the hatch date, it is difficult to be more specific. Adult Bettas are about 3 inches long. They reach this length anywhere between 7 and 12 months of age. His eyes are dark, his color is good and his fins are long. He's at least a year old. That would be my best "educated guess" based on the images provided.

While she is a baby, you can feed her twice a day. Only feed as much as she can eat in a minute or two. If you feed too much the feed will fall to the ground and then contaminate the water.Later, when she is grown up you can change to feeding her once a day. Your fish figured out that you feed her when you come near the tank, So it is fairly normal for her to beg.

Allow the male and female to see but not reach each other. When the male is ready to mate, he will build a bubble nest. When the female is ready, she will "bar up" and develop vertical stripes. At this point, they can be introduced to one another for breeding. The time for each fish to be ready depends on age and environmental factors.

Beta fish lay eggs and she would need a male to then fertilize those eggs after she lays them. Breeding betas can be very work intensive. Here is a link with great information: fishkeepingworld.com/breeding-betta-fish/ As the babies get bigger, they can graduate to larger food. The babies will mature and need to be separated around 3 months of age. The females can stay together but all the males will need to be separated. Breeding betas requires a lot of tanks/space. I recommend to connect with a local aquarium store and find out if anyone has first hand knowledge. I hope this helps and please feel free to post any additional questions.

She appears to have eggs given her girth. There are also some vertical bars on her side that indicate she may be ready to spawn. If possible, check underneath for a pronounced white dot. This is further proof that she is ready to spawn.

Mushu is very cute! Betta care is very easy. Ideally, a 5 gallon tank should be used to house your Betta. A smaller tank can be used, but the maintenance (water changes) will be much more frequent. A filter is always recommended otherwise water changes will be required every few days to maintain water quality. With a filter, 20% water changes can be done weekly or every two weeks. Use only aged or conditioned water that is temperature matched to prevent stress or shock. Choices for conditioners include AmQuel Plus, NovAqua, StressCoat, Prime or StressZyme. A small submersible heater is necessary since Bettas are tropical fish. They do best in slow moving water between 78F and 80F. You can feed a pelleted diet such as Hikari Micro Pellets until he grows bigger. Baby brine shrimp, daphnia, bloodworms and blackworms can also be fed. Feed one or twice daily. He should only need 2-3 pellets at each feeding. The conditioners and food can be found in the aquarium section of the local Petco. Please request a consultation to discuss care in greater depth or post another question in the Forum if necessary.