It looks as though your rabbits decided on their own that they wanted to be bonded. If you decide to continue, from the sound of their first encounter, the rest should be pretty easy.
Though I do believe spaying and neutering is usually best in most circumstances, I'm not one that believes that rabbits can't be truly bonded if they aren't fixed. Usually with males it is more necessary as they are so hormonal it almost always gets in the way of bonding being possible(and can be very dangerous because of fighting, and next to impossible when attempting male/male bonds, which I would never suggest attempting). With females though, it's more possible for an unspayed female to bond if you have a female with a personality that makes this possible. I had a bonded pair where the male was neutered and the female unspayed for the first two and a half years of their relationship, and they did just fine together. She did tend to hump him more than an spayed female would, but he is pretty easy going and she didn't do it so much that it irritated him. I did eventually get her spayed and their relationship hardly changed at all, except for less humping going on. So it is possible with the right rabbits, in the right situation. You also need to be aware that if she humps too much and it irritates him, it could lead to a fight, but this can also happen in bonding where both rabbits are fixed. And also be aware that if you bond them, that you can't usually separate them back to single buns without it causing a lot of upset to the rabbits, even can cause real depression with them. So once bonded they need to stay that way.
I would however, suggest to wait a few more weeks if you decide to go ahead with it. You only neutered him a week ago right? So he can still have viable sperm for up to 4-6 weeks post neuter, and could still make your female pregnant. You should wait at least another 3 weeks(5 if you want to be really safe) if you don't want to end up with baby buns. Though if he humped her at all when you let them be together, she could have possibly gotten pregnant already.