Hmm.
This is an interesting question. There are a lot of different perspectives you could take on it, in my opinion.
***You would think that since St. Joseph is considered the foster father of Jesus, he would have some pretty serious intercessory power. So if any one of the three saints you mentioned had more intercessory power than the others, you would expect that it would be him.
Now, you could look at your situation in a few different ways:
(1) St. Joseph and St. Patrick intercede for you just as much as St. Anthony does, but it wasn’t God will that your prayers be answered until the time you started praying to St. Anthony. So, it ended up looking like you got results because you started praying to St. Anthony, but really that is just when it was God’s will that your prayers be answered.
(2) St. Anthony IS a more powerful or frequent or what have you intercessor compared to St. Patrick and St. Joseph. But for some reason, that doesn’t make sense to me assuming that you accept***.
(3) Then again, you could also think that St. Anthony might have had some special interest or dedication to your intention, so his prayers on your behalf were “better” for your intention. It seems sort of silly that your prayer was taking such a long time to be answered just because you hadn’t chosen the right saint to pray to.
(4) Finally, it could just be that things happened to work out when through coincidence when you started to pray to St. Anthony. Had you decided instead to pray to St. Therese instead of St. Anthony, you might have been left wondering if she had more intercessory power than St. Joseph and St. Patrick. Of course, most everyone is going to say that nothing happens by coincidence, and this option will be rejected.
I think (4) is the right answer, though. I think it was coincidence. It just happened that way. It had nothing to do with which saints you had prayed to or had decided to start praying to.