OP, I got hearing aids a year ago.
I tried the in-the-ear aids first, as, like you, I wanted them completely hidden. The audiologist had said behind the ear would be far better in terms of quality of sound, but I wouldn't be persuaded and so she ordered me the in-the-ear aids.
I hated them. Because the microphone is nearer your jaw, when I was eating I couldn't hear anything except the sound of me eating. At our work Christmas dinner I actually had to take them out because I couldn't hear a word of what anyone was saying.
And even when I wasn't eating, I just really didn't get on with them. I didn't like the feeling of my ear being completely blocked by them; every little tiny sound was so amplified that it drove me mad; I wasn't convinced they helped me hear speech any better; and thought I was going to have to give up wearing aids completely.
After a month I changed them for the behind-the-ear aids. They were revelationary. So light and comfortable, snd great sound quality, and even now, a year later, people at work have not noticed that I am wearing them. When I met up with friends for coffee etc, they didn't notice until I told them.
I would echo what PPs have said - go to Specsavers/Boots and have a free checkup and see what the audiologist recommends. They may have a behind the ear aid that you can try, so you can see for yourself that actually, if you have aids with a dome rather than a mould, they are really hardly visible at all.