I bought a pair of love bird in October but after three week female bird fly then I bought a female bird same day but it almost 7 months they don’t breed yet why and today I rescue a female bird and I kept it in same cage is that okThree would be fine together in most cases. you just have to be VERY careful when introducing them. I would recommend getting them all the same sex though. Two males may fight over one female. Two females and one male would be fine.
HOWEVER, I do not recommend getting any other lovebirds if this one is intended to be a pet. Once you introduce more (Especially if they are females) they will almost always get nasty towards humans. Males are more tame and won't jump out of the cage to attack, but females WILL. LOL, and they sure can be painful! Also, a pair of lovebirds will breed and breed and breed. For some that could be a problem.
If you do decide to get a third, try not to buy it from a pet store. See if you can find a breeder, or better yet adopt. So many lovebirds end up without homes because people don't realize what kind of pets they actually are.
Good luck and if you have any more questions feel free to ask! I work in an exotic bird sanctuary and have experience with almost all types of parrots, large and small.