No experience with CPM network which approves adult site, but in general I have had good experience with Adversal and Qadabra. Both have been performing on the expected lines for different niche websites like Health-related, Travel-related, Food-related and Ad Network related sites. You may like to try both of them out and see how they perform for you. Other than these two, you may try out Pulsepoint and CPM Go also as they do not require any minimum number of traffic to get approved by them. You may refer to below article - it would prove to be helpful for a new webmaster - adsreview.in/cpm-publisher-networks-with-no-traffic-requirement-the-top-5
Qadabra big no no their rates are worse with thousands of impression you may end up making only 1c or so check other related thread Adversal have no experience and check if they accept adult site