Yup. Totally uneducated crap. Source: my almost 12 year old daughter.

We only had sex once, he pulled out but still came 'on' me - not in me.

It only takes one sperm during your fertile period. And unless you're actively tracking (daily mucus observations, or other indicators I don't know much about like body temp), you don't know when that day is - mine varies by days, even when my cycles are the same length.

And I agree, your guy rode over, wheedled his way out of or plain ignored all your boundaries. This is a huge red flag for me, and others commenting here too. Saying no, but letting him ignore that could put you both in a bad position later where you want him to stop and he doesn't - which is rape - because he's used to you saying no then giving in. And getting him to pay for anything like Plan-B could be seen as letting him buy his way out of bad behaviour.

Besides an unplanned pregnancy, back to front is just asking for a uti.

I get that it felt good for you. But if you don't want a pregnancy or uti then you need to be smarter and stronger.