It depends on how you're bullshitting, the manner in which you're going about it. There are myriad ways to bullshit.
Here are a few possibilities:
You could say that you're "dissembling," giving a false or misleading impression to conceal the truth or the real nature of the situation, which is that you don't know what the hell you're talking about.
You could say that you're "quibbling," using ambiguous, prevaricating, or irrelevant language or arguments to evade a point at issue or making any clear point at all, which is common with bullshitting because you don't want to commit to a point because it could be wrong and get you marked down.
You could say that you're "verbigerating," a backformation of "verbigeration," the act of constantly repeating meaningless words or phrases.
You could say that you're "making it up as you go along," which isn't very fancy but isn't informal, either, and is how a professor of mine would have said it if they didn't want to curse by saying I was bullshitting.
You could say that you're "fabricating" the paper, which is a more concise way of saying "making it up."
You could say that you're "perseverating," repeating stuff and being redundant just to add to the length.
You could say that you're "being sesquipedalian loquacious," using big words to say very little in a lot of words, hoping to give the impression you are saying a lot.
You could say that you're "pleonastically palavering," which is speaking profusely in a manner that flatters, persuades, or cajoles while at the same time stretching it out by using as many words as you can.
And now the coup de grace:
You could say that you're "floccinaucinihilipilificating," a backformation of the noun "floccinaucinihilipilification," which is the act of assigning something extremely little or no value, which is what you're doing to both your words and to the assignment itself.
The word "floccinaucinihilipilification" was coined by some boys at Eton College in England after teachers went on about the "honorificabilitudinitatibus" (which is the longest word Shakespeare ever used) of Shakespeare's works, indicating his works were worthy of many awards and highest honors, and a group of boys at Eton who didn't agree, who thought Shakespeare's work was bullshit by a bullshitter, coined the word "floccinaucinihilipilification" as an even longer word than "honorificabilitudinitatibus" to express that opposite idea, to deem it all to be worthless bullshit.