The Force is infinite. You are not.
When I first joined Chaos, one of the first things I asked about was dueling. After all, on my old site, I was a top ranked competitive duelist. I enjoy dueling. When everything goes well, it's some of the best fun you can have on a Star Wars RP site.
It took me a while to wrap my head around that philosophy, because the idea itself was so alien. On the old site, there were strict rules on what you could and couldn't do, largely because various asshats had done something stupid over the years, and we had to be able to tell them no.
After a few weeks, however, I came to embrace the idea. It was very much in line with my own personal philosophy on the Force. As I've always written it, the Force is largely a matter of perception. If you believe it behaves in a certain way, then it does. It was a little unnerving to see the idea practiced en masse at first, but I got used to the idea.
It became apparent after watching a few invasions that there are a great many of folks that take the first sentence to heart, but sort of forget about the second part. People get really creative with their use of it, but forget that their characters are mere mortals. A fight without limits quickly devolves into a game of oneupmanship, and down that path lies much butthurt.
A large part of the problem stems from the fact that a text based format really doesn't offer any concrete way to gauge a character's limits. Without a mana bar, how are you to know when your Force use has become excessive?
I've put a lot of thought in the matter, and I've come up with a little mental exercise that should help visualize the problem.
Close your eyes and imagine a simple circle. Now imagine that circle is spinning counterclockwise at a continuous speed. Try to hold that image for as long as you can. For some folks, it'll be fairly easy. For others, it takes real effort. Once you've got the circle held firmly in your mind's eye, turn it into a wheel. Doesn't have to be anything fancy, just some spokes and maybe a little rubber for a tire. Gets a little more complicated, right?
Now try to hold that spinning wheel in your mind while doing jumping jacks or running in place or something.

With a little practice, most folks would have no problem holding that wheel in their mind for a little while, even during exercise. They might even be able to up the complexity by adding more detail, or even more wheels. But after a while, fatigue starts to take its toll, and focus becomes harder and harder to maintain.
That's about the best way I can think of to demonstrate what it might be like to use the Force in a fight.
See, Force powers, from the smallest push on up to Force Light or Spear of Midnight Black all require some level of concentration and focus. This is canonically one of the reasons most Jedi spend years learning to meditate and clear their minds, and why Sith have to learn to focus on whatever passions and feelings drive their powers. Sitting in a swamp levitating rocks is one thing. Trying to levitate rocks in the middle of a firefight is an order of magnitude more difficult.
With sufficient training, most Force users will be able to access certain powers almost instinctively. They might be able to Push or Pull or even do something more complicated like hold a barrier with little difficulty. They might also be able to use the Force to augment their physical stamina.
After a while though, you're going to start stacking too many of those wheels, and you're going to start dropping them. Fatigue also takes a toll. If you've never been in a physical altercation, it's hard to describe just how exhausting it can be. A few seconds in a fight can seem like hours, and a few minutes are an eternity. It's exhausting on all levels.
Add that in with the physical pain from injury and focus becomes that much more difficult.
As I mentioned earlier, the Force can be used to counter fatigue to a certain extent, and it can also be used to sharpen focus. But at the end of the day, your character is just a mortal. There are limits to what even training and experience can do, and if you have an interest in writing fairly, this should be reflected in your posts.
It's also worth remembering that, in all likelihood, your character is going to have a particular skillset that use more often than not. If you watch professional fighters, they all have a certain style they like to stick to. They move in a certain way. They hit in a certain way. They like to maneuver the fight to play to their strengths and to cover their weaknesses. This is especially evident in MMA fights. A strong striker will try to stay on their feet and deal out damage with their fists and feet. A strong wrestler will go for the takedown, where they can force a submission. A fighter with good endurance might try to drag things out, wearing their opponent down until they make a mistake.
They might be able to try something new or more complex, but it takes more effort and concentration, because it's just not something they're as familiar with.
Ideally, it should be the same with the Force.
As always, if you have any comments or questions, my inbox and the comments section are open.