Game balance is Relative
There's no real way to determine if it is unbalanced per se. What it obviously gives you is versatility. Have a repertoire that can be custom fit to any situation is incredibly valuable. But, balance is relative to a few factors.
If your wizard is far more versatile than other party members, they may feel like you're overpowered. A non-combat focused Warlock might feel like he is less powerful because you can do his thing AND combat things. Or, a player might feel like you're killing everything and they aren't pulling their own weight because the DM has scaled up his encounters to fit you, which brings us to our next point
Your DM ultimately has control over what is being thrown at the party. There's basically no way for you to be too powerful for him/her since they control the difficulty of encounters and other things. Being versatile has it's benefits for both of you, since the DM can throw intrigue, combat, hunting, or anything your way and he doesn't have to worry about you not being able to handle it. On the flip side, he might want you to be outside of your comfort zone by throwing something you havent planned for, and your versatility is defeating that purpose.
At any rate, you should check with your DM and your party if this is acceptable behavior for your wizard. They all need to be prepared for you to have a huge arsenal of spells and plan accordingly.
"A Mary Sue is an idealized and seemingly perfect fictional character, a young or low-rank person who saves the day through unrealistic abilities" (Wiki). Your character is a story in the making. Having a character that can "do it all" might feel like poor character creation to some. The spells your wizard chooses can (sometimes should) be influenced by your characters background, ideals, and flaws. Jack of all trades, master of none can certainly be a character flaw if you play it right, but you should be mindful of what this playstyle means for your character and more importantly, you party's characters and the DM's setting and story.