What a great question, thanks for asking. I handled my sole vampire (so far) in a very specific way, actually. I did some things that you also do, kami12, like not eating mortal food, sleeping during the day (or at least waiting in a shady spot, if there's no indoor location nearby when sun's coming up).
I was dismayed to find that Dawnguard changes vampirism, so that NPCs only freak out when our character is in Vampire Lord form. I liked it the old way, the way TES4 handled it: NPCs freak out if our character makes it to Stage 4. I like that there is some pressure to get feeding done, that there is an actual reason to feed (beyond pure roleplay). So I actually disabled Dawnguard for her game, and only her game.
I also never liked how 'soft' the method of feeding is, in TES4 or TES5. If a human or elf is getting their blood svcked, there should be some level of drama. Maybe I've been spoiled by what I see in movies, but I can't buy somebody just laying there while they are being fed from. They should either (1) attack, (2) resist the feeding, somehow, or (3) totally freak out and flee. Nobody is going to just lie there asleep during this process, or merely stand around (as they do in Skyrim with Dawnguard activated).
So what I did to 'fix' this is sort of bizarre. Here is how I did it, step by step.
1). My vampire would usually break into somebody's residence.
2). She would feed, if possible.
3). She would either attack or cast some sort of non-lethal spell (this is to simulate the NPC struggling).
4). The NPC awakes. Oftentimes, there is some reaction ("Get out of here") or attack.
5). My vamp would 'hypnotize' her vicitim, as vamps often do in lore, to calm him or her down. (This got simulated by casting the Voice of the Emperor spell. My vamp was Imperial).
It's kind of fudgey, I know, but it worked for me. After hynotizing the victim, that victim would typically go right back to sleep, or some other mundane activity which suggested he/she had just forgotten exactly what happened. I like to think that when this NPC awoke the next day, they'd have some vague recollections of a terrible dream, and wonder why there were strange marks on their neck.