I'm starting to. It's much easier to draw my own characters in that situation rather than some other franchise or going straight into commissions - as long as it's the ones that truly would be okay in a sexual situation. No minors, no age-ups, no ace unless their character would agree with an SO, no overly objectified subjects especially if the character in the story had that problem. If it ain't okay in canon, it ain't okay in my weird noncanon ship either. However, they get posted to my not so secret Pillowfort, since it's got good NSFW rules and I didn't feel safe at all making a new Twitter.
If it's in a space away from people under 18, there's nothing to be ashamed of. Consenting adults in pictures, the only thing I'm afraid of are other people ashamed of themselves that call the artists disgusting for daring to be sexual which is a big problem on Twitter. And, to stop feeling like that, I'd say thinking of yourself as unclean and wrong? If you're not doing anything fucked up in any way and it's not exposed to anyone that doesn't want to see it, what's really the problem?
On your last post, You'd be surprised at that bits part, especially if the characters are fantastic, monsters, aliens or all three. It's a real part of character design, with all the design pitfalls that entails.