Hey Loopsyme,
Our most up-to-date emergency contraception piece can be found here:
Emergency Contraception (Plan B or the Morning-After-Pill).
That piece states that Ella is "slightly more" effective than Plan B and other levenogestrel-based ECs. It also explains that Ella can be a better fit for people with a higher body mass index (BMI). Plan B is less effective for people with a BMI of 30 or higher, whereas for Ella that is true for a BMI of 35 or higher. In addition, it explains that Plan B's effectiveness rate can drop by up to 15% once the 24-hour window after the pregnancy risk ends. Ella is just as effective later on (up to 5 days). So those are some ways in which Ella can be a better fit for someone. The piece says nothing about Ella being "worse for your health" than Plan B, so no need to worry about that.
But I also want to check in about the birth control failures you mentioned. You said earlier on that you are using condoms with you partner. When used properly, breaks are quite rare with condoms, so this can likely be easily fixed. Are you using plenty of extra lubricant? When you put the condom on are you leaving room in the top of the condom for your partner's ejaculate? Are you storing the condoms properly? A bit more on proper use of condoms:
Condom Basics: A User's Manual.