Have you upgrade your cards?
The type of cards is actually similar to the ones I use, so I don't think they are a big problem. However, the low level is. I would recommend only using cards with 2 or 3 stars, and put them at least level 7. When you combine them in the Workshop, pay attention: if you combine two different (nude or not, big breast or not) cards of the same level, the result will be a card equal one of the ingredients (random). If you combine cards of different levels, the result will always be equal the ingredient of bigger level. So I normally combine two equal cards to put them on level 1, then I add all random cards avaliable.
Other tip, dolls with hunter cards die earlier, because they dont care about their own safety when they are looking for their targets. But when a doll dies, the card they were using drops, and other doll can pickup and stack their bonus. So, if your dolls are dying early, is essential to pick up their cards. Alternatively, you can use cards that dont make you dolls hunt anything, so they will survive longer. I suggest "bit magnet", "guardian", and the resistance ones. But using hunter cards or more passive ones is a choice of gameplays, and both are viable to get maximum level.
I like to use 3 cards that give huge attack bonus and 1 that gives huge speed bonus. But this is just a suggestion.
The setup I used when I get to max level (still only got there one time) was a level 10 Nicole (whatever color), a level 10 Adult Ruby Rose (red) (one level 10 Adult Mabel red would be better, but I cant get this stupid card), a level 8 Cerebella (blue) (I still wasn't able to upgrade it to level 10), and a level 10 Adult Ilulu (purple) (a upgraded purple Tifa Lockhart could do the same job. During the game, I would use only the doll with the Ruby Rose to get the balls, and control only the doll with the Nicole during the game. The doll with Nicole was a level 4 dog. The level of the dolls are also extremely important to get max level, because how strong their skills get at this level. If your dolls still aren't on level 4, you need to grind a little more :P