It is really tough to tell while you are doing the activity…or even for someone watching.
The effort level may have been higher. You may have a mechanical issue that is holding things up.
I will say this. Developing velocity is a process that takes patience and dedication. Every person is an individual with different natural body motions, advantages and limitations. Every person has different training and injury histories.
My sons velo (first time being gunned) when he was a soph in HS was 74 mph. As a Junior it was 78 MPH. As a Senior it was 76 MPH. Now, it swung up and down in 2 mph pieces over that time frame. He was playing other sports, so, if he was playing basketball and running tons he would lose weight and he had to cut back on throwing. If he was playing baseball, obviously he was throwing more and his arm got conditioned better and he was working on mechanics.
He injured his elbow prior to his senior year. We thought the season would be scrapped, but, he got some treatment and struggled through a bad senior year, throwing mid 70s.
He is anywhere from 82-86 now depending on the day. The one thing that was missing all of those years of playing other sports and trying this thing then the other was the simplest of all…establishing a good base. A good base of throwing, mechanics and fitness. After working the last six months in a pretty dedicated way he now, finally, has what I would consider a solid base. Meaning he has some strength, his arm is conditioned (he can throw 100+ pitches and experience no measurable soreness the next day) and he has a firm grasp on what he is trying to improve mechanically.
Most guys do not experience a linear climb in velocity. In other words…a guy does fill in the blank and gained 4 MPH. Or, a guy should gain 2.5 MPH year through high school. It just doesn’t work that way for most guys. Some guys start a program and have big results in a short period of time then plateau (a big early gain usually indicates a lack of training prior to starting the program or a major issue being addressed), some guys never have a big jump, they sort of chug along and are more consistent gainers. They make gains 1 or 2 MPH at a time, they still experience plateaus but they usually don’t last as long as the guys who have jumps.
So, I sense frustration in your post. My point is it takes patience and time. Work now on establishing a good foundation. Mobility, mechanics, strength, conditioning your arm, a solid foundation in these things and you should have a base to build velocity gains on.