You have to look at your children separately, and I mean totally separately, in this regard. Your 3 1/2 year old isn't even in the ballpark of your 5 year old. There is a part of the brain that tells the body to stop producing urine at night when sleeping. It has to develop in order for your daughter to stop needing to pee in the middle of the night. She is PERSONALLY not old enough for this to happen yet. Some children's brains do actually reach this point at 3 1/2, but it's not a usual thing. My ped told me point blank that daytime toileting and night time toileting are not the same and that I could not expect my sons to night train before they were 4 years old. He told me that the best thing to do was to use diapers until they were able to go 4 nights in a row dry. THEN put on underwear. Tell them every morning that they are dry that you know how proud they are of themselves for having a dry night. When they wet the bed, you hug them and say "Aww, I know you were hoping for a dry night. I'm sorry, honey. We have to put on diapers again until you have 4 dry nights in a row. Here's a calendar. We'll put a check mark on each night you have a dry night. When we get 4 nights IN A ROW, we'll put gold stars on those 4 nights, and go back to big boy underwear!"
That helps take pressure off of them to perform, YET it also sets up the expectation that they are capable of doing it and that they are supposed to be proud of THEMSELVES for reaching the milestone. Not that you are supposed to be the one that is proud of them.
And you don't start this process until they have a fighting chance of being successful.
It's nice that your daughter made it 5 out of 7 nights. I would employ this strategy with her. Perhaps her brain can do this. I would NOT expect it of her. And I would not use a pullup with her. A diaper will help her FEEL the wetness. You do want her to feel the wetness.
As far as your son is concerned, it very well may be emotional because you are pushing too much. You might not think you are pushing, but HIS perception is what is important - not yours. I'd employ this same strategy with him (except that you may not be able to find diapers so large for him, so pullups may need to be what you use.) If you go to bed a few hours after he does, try waking him enough to take him to the bathroom and see if that helps.
Some children sleep so deeply that it's like waking the dead to get them to pee. My older son was like that. He couldn't even seem to let go because his brain didn't understand that he was on the potty. It worked with my younger son fine. I didn't have to do it for long. They both night trained pretty easily. I did the strategy I talked about from the get-go (because the ped told me to do this upfront) and it worked very well.
Another thing to remember is that some children just will not feel the wetness enough to wake, and there are "alarms" that you can buy to wake them when the sensors feel the beginnings of wetness. My niece had one of those. And yes, she was one of those kids who peed the bed for several years. It does happen that there are kids who don't finally stop doing it until they are teens.
I don't see any indications that that will happen to your child. However, it's too early at 5 for you to be worrying about that.
Try to ratchet down on the expectations and maybe that will take the pressure off of your 5 year old. The next time you see the ped, talk about when to think in terms of a medical response (like the alarm) and other alternatives. It's too early for those at this point.
Good luck,
Dawn