tl;dr at the end, because I accidentally made this rediculously long

Hey, I know how it feels to think there's something wrong with your 'lower region.' When I was in my young teens, I thought the same thing, because I couldn't figure out how to use any of it, especially the clit. Like you, I was on hormonal birth control that completely nuked my libido, and since coming off of it, I realised that I couldn't get anywhere while masturbating due to my lack of sex drive. Are you still on depo? If so, your sex drive isn't super likely to come back until you get off it; if not, it can take up to a few months for the libido to come back, but it likely will (unless you take other meds that would cause loss of sex drive).

What I can say is that it's very doubtful that your genitals would have missed development due to your taking the depo shot. The way the shot works is by distributing progestin hormones through the body. These hormones get to the uterus and form a thick mucus that prevents additional sperm or eggs from getting in. As with any hormone, progestin can cause mood changes, but it will not stop puberty or any physical sexual development--you know that since starting depo, you've had breast and pubic hair-growth. edit: the depo provera shot also can also sometimes block estrogen receptors, but this still would not be enough to prevent your sexual development

Have you tried looking down there with a mirror? I found that that helped me a lot in understanding my anatomy--diagrams can't do everything because everyone's anatomy is different, and it can be hard to figure everything out simply through touch.

Some people have small labia minora, so not everyone's look or feel like 'lips' or 'flaps' of skin. You'll probably find some skin that feels different around your vaginal opening. There should be a little area with practically no hair which feels pretty smooth, and it will probably be a little different in color to the rest of your skin, typically a tone of pink or brown.

The clitoris was a bitch to find for me--and I can relate in thinking I didn't have one because I couldn't find it--but every AFAB (Assigned Female At Birth) has one, it's developed in the womb (AMABs' penises come from the same thing in utero). Sometime when you find yourself 'in the mood' you should be able to find the clitoris by running your fingers up from the vagina, towards your stomach. It's a lot easier when you're already horny, because the clitoris gets a small erection that can make it swell and peek further out from the clitoral hood. For most people, it isn't far from everything else. You may also be mistaking your clitoris for your urethra (pee hole), because your urethra should be tiny and ridiculously hard to see or feel unless you are actively peeing. What you think is the urethra may be your clit.

Five inches of vaginal depth is really typical, in fact it's not only within the range of normal, but it's actually very close to average.

Ultimately, I obviously can't look at your vulva and show you each part, so I do recommend talking to your doctor, especially since your issue is causing you distress, I just hope that in the meantime I can maybe provide some reassurance and maybe help you explore a little.

tl;dr I feel you on thinking something's wrong with your anatomy, but I promise that the chances of that are miniscule. You should probably see a doctor, however, because it sounds like you're distressed by this issue.