Gyno told us to use secondary form for first month of new bc... condom failed...

So here's the story. I was previously on Loestrin 24, and recently switched, as in started ortho tri cyclen on February 9, the day after the brown "period pills" from my Loestrin ran out. The gynecologist told us to use a secondary form of birth control for the first month. I'm not sure why, my body needs to get used to the hormones or something? Actually, this is what my mom told me passed ON from the gynecologist.

So we chose condoms. The other day while having sex, it broke. We noticed this when he pulled out. I immediately stood up, a lot fell out. I know this is not a valid method, but it's worth mentioning, just keep reading. We noticed also that some of it was on the walls of the condom, so it broke at the very end.

We thought about it for a while, and considering I'm probably nowhere near my ovulation date being about five days after my period ended, the fact that a considerable amount obviously did not "go in", and the fact that I've been on birth control itself for over a year, combined with my history of irregular cycles and ovarian cysts, my chances of pregnancy seem low.

I'm still going to get the plan b pill tomorrow as I'd rather pay $60 now than $400 at the end of the month for the abortion pill.

But just out of curiosity: does the secondary method of contraception rule apply towards people who are totally new to birth control more? And am I less applicable for this rule since I've been on birth control for a long time? My body is reacting very well to the hormones, I have no breakthrough bleeding like I had starting Loestrin or any other symptoms that were mentioned, like nausea. Was this just something my mom was saying to deter me, or my gynecologist was saying just to be extra safe?

Please, I really need advice. My boyfriend and I obviously cannot afford or emotionally support a child by any means. And I'd really like the peace of mind knowing that plan b within 48 hours can significantly reduce my chances.

The thing is, plan b isn't 100% effective, and it lessens as each day goes by. I will be getting it in less than 48 hours after the incident, but I want to know if my pill under my circumstances is at least SOMEWHAT effective or not.

I'm not sure if my question made sense or not.