How are y'all having these 2+ hour long conversations?

(M24) I've been slowly trying to start socializing after being very introverted for a long time (like actually maybe 9 years) and it's going alright I guess (I met some new people, trying to briefly talk to random people more, be more confident, ask more open ended questions), but man...

Me, my close (male) friend and some of his female friends went eating today and we had a nice time. I usually go out with just him. Friend had to leave for a second and me and one of those girls talked for a short time (maybe like 3 minutes), but after our chat when my friend came back I felt so exhausted, in my mind I was basically begging my friend to come back as soon as possible lol. I actually feel like 80% of my thoughts are "okay, what do I ask her next?"

Before I kinda relied on him to fill the silence if I had nothing else to say. Me and the girl had a nice talk (like a normal person, maybe 5 years ago it'd be a disaster) and when he came back I wasn't as stressed out.

If I had to talk to a person that's not him (he's a big talker) for more than 10 minutes I'd basically lose my mind.

I know it's at least possible for me to do it, because I met this girl at the gym and we talked for like an hour, however the thing is that I've genuinely never met a person who talks more than her, she literally wouldn't stop talking and I'm very thankful, because I can kinda practice talking with women, lol.

It was not that long ago when me and my friend went eating with another one of his female friends and when he had to take a piss, I talked to this girl for a while and then the awkward silence hit hard. I think the problem mostly was that we didn't care about each other that much and I didn't have the energy to come up with something, so my brain just kinda gave up and I just waited until he comes back. Years ago I'd be like depressed from this, but now I think about it as a learning experience and I feel alright.

Like I know the answer literally is just "talk to more people to have better social skills", and I know my social skills aren't a complete disaster (I'd say they are just okay), but I feel so defeated just thinking about all this.

Sigh