Hi there, welcome to the boards!
Condoms are about 98% effective in one year of "perfect use". This means following all the manufacturer's instructions - you can read more in our piece about it here:
Condom Basics: A User's Manual
Essentially, you want to follow the steps outlined in that article closely - ejaculating in the condom is okay and as long as those steps are followed, it is generally safe. Blowing air into a condom isn't necessary, as condoms don't really tear in a way that you'd even need to do that. You would know if it ripped as the semen would leak out, and your partner would likely feel it happening in the moment. It's still okay to visually check, but if the semen isn't leaking out and the condom looks intact, there's no need to blow air or put water in it.
All this said - since condoms are not 100% effective, mostly due to human error, it's never a bad idea to use it as a backup to birth control (essentially, use both together). So if getting on birth control is something you're able to do, I do suggest going that route so you can really feel safe having sex.
Here's more info about condoms, and if you scroll to the bottom, you can read about other birth control methods too:
Birth Control Bingo: Condoms
Let me know if you have any more questions!