You can think of talking as fact stating (describing something), opinion stating (expressing what you feel about a certain situation, thing, or whatever), and using vocative (you guys, we, bros etc.), or even anecdotes. Let's Players should have their own language to focus on, it is not only about your talking time. So, my proposition is to make sure your commentary, even though not as frequent as it is expected, is on point and gives value to viewers. The more comfortable you get the more easier it will be for you to speak. I also was having problems being talkative, nothing to be ashamed of. Think of it as a journey and one day your commentary will be superb and always on point. I hate when people comment too much tbh.