Nobody answers my CQ's...
While not against the rules, calling "CQ" on an FM or digital voice repeater is frowned up in most amateur radio communities.
Calling "CQ" is useful in situations where you are looking for someone to talk to and you are hoping that somebody tuning through your frequency will hear you. This is often the case on the HF frequencies where tuning the VFO is how we find conversations (before the days of panadapters and spectrum scopes that allow us to visualize where the signals are). However, repeaters are channelized. While some folks scan repeater channels, it's not a matter of slowly turning a VFO and watching for the S meter to deflect on someone's call like it is on HF.
A more generally accepted approach on FM and digital voice repeaters is to key up and say "KD9ABC listening" or "KM4XYC monitoring". That lets people know that you are there. If they want to talk to you, and that's a big "if", they'll key up and respond to your cal.
Another approach is if you hear a conversation on an FM or digital voice repeater and you think you can add something to the conversation, key up and just give your callsign. Hopefully, someone else in the conversation will recognize your call and turn the conversation to you. It's good practice, whether joining the conversation at a social event or on a repeater, to make sure that your comment can add to the conversation. If the folks talking are discussing last night's ball game and you jump in with a story about what your cat did last night, you might not get a warm welcome.
Ham radio operators can be very social. Some of them will welcome you with open arms and immediately become your best friend. Ham radio operators can also be anti-social and clique-ish. They may not be too welcoming to new people.
One technique that can help break the ice is to attend local club meetings. People will get to know you face-to-face and they may be more likely to talk to you on the air.
Now, after all this social engineering talk, we need to talk about your signal into the local repeater. If all you are using is a handheld radio with a rubber duck antenna, you may not have a very good signal into the repeater. You may hear the repeater well and you may get some acknowledgement from the repeater when you key up, but your signal may not be strong enough to produce a readable signal for others listening to the repeater. If what people hear when you key up and give your callsign is "K-scratch-five-shuff-M-brappp", they aren't likely to respond. Your radio has an S-meter. Move around when you are listening to the repeater and find the spot where the signal is highest, preferably at full-scale. Stay in that spot. Don't move the radio as you talk. RF does funny things and moving your radio just a few inches may take you out of the hot spot.
A possible solution is a different antenna. No, I'm not talking about one of those whiz-bang after market rubber ducks that the YouTubers promote. They may help a little, but the differences are slight. When using a handheld radio, one thing that will help is an antenna in a fixed location. Yes, we'd all like to have a high-gain base antenna, but that's not always practical. A first step could be a roll-up J-pole antenna. MFJ, Ed Fong, and N9TAX all make good roll-up J-pole antennas. Get one of those and hang it from a tree limb or a thumb tack stuck in an inside wall of your house. It might make a big different in how well you get into the repeater. One rule about J-poles is to keep them away from anything metal, such as a window frame, because that will affect the antenna's performance.
Don't give up. I was in your spot once. I lived in an apartment and couldn't have outside antennas. But, I still found ways to get involved and have fun with amateur radio.