Lots of good advice here.

You either didn't say, or I missed, how long you have been riding overall. You said since February, but how many years?

I ask because I used to get a lot more of what you're describing when I was in my first year or two of riding. A LOT more. I did a multi-day tour with rides up to 80 miles my first year, so I'm not saying newbies can't go far, etc. But, I do notice that the longer I'm at it, even pushing harder to do more and more, I get what you're describing less and less. I don't know if that has to do with better fueling, more self-knowledge on the bike, or whatever, but there it is.

Also, and this is probably just due to my personality type, I notice that when I ride alone, I feel freer to just really take care of my own needs -- stopping if I need to, eating exactly when I need to, etc. When I ride with others, I tend to put off eating if the pace is high and I feel the need to keep up, or I just don't stop if I feel the need, etc. In the long run, riding with others probably would make me faster by getting me past stopping a lot, etc. But, the added little stress of a group or riding partner can make me a little crankier if it means I'm pushing, pushing, pushing and having to keep someone besides myself in mind.

Just some other stuff to consider...