Anal Help

Hi ladies so I've always been very anti-anal sex. It's never been something I even wanted to consider. But my boyfriend said he wanted to do it the other night. And since he's considerably more experienced than I am I didn't immediately shut him down. We talked about it a little bit but he really couldn't answer all my questions. He isn't pressuring me in any way- he's very adamant that I'm 100% comfortable with this. He tried just using his finger which felt really really weird by it didn't hurt. But it was only for a few seconds because I just got too nervous. Anyways I'm just wondering if anal can actually feel good? My boyfriend is very well endowed and I'm really not good with pain at all. And I'm really worried about poop- I can handle period sex no problem but if poop became involved I really couldn't. I won't douche because it's so unhealthy for you but is there anything you can do to ensure there's no chance to poop? And any other suggestions?