Your schedule is close to 50/50 but your agreement should also specify who has the child on Tuesday between school drop off and school pick up. The reason for that is in case the child is sick or there is no school on that day, it is clear whose time it is with the child. If you have your daughter until Tuesday at the end of school, I would consider you having an equal timeshare because then each of you have 3 and 1/2 days. I think that would be an appropriate change to make to your written agreement to make it equal between both of you.
What makes you think you are not getting 50/50 custody? regardless, if you want to seek a change in the custody order you will need to file a motion with the court. It would be best if you at least consulted with an attorney before proceeding. Many attorneys, including my office, offer free consultations. Good luck.
Jason A. Ewing is a family law, criminal defense, personal injury and civil litigation attorney in Sacramento, CA. Mr. Ewing can be reached at 916-759-7645 or email@example.com. Please be advised that although Mr. Ewing is an attorney, the comments posted do not constitute legal advice. You should not rely on any advice or suggestions written and seek outside, independent counsel. An attorney-client relationship has not formed by reading the post.
It appears from what you describe you are receiving 50-50. However, to be certain you should meet with a lawyer in their office in the county where your case is pending. Too much is at stake to "gamble" and go into court without all the legal knowledge you might need. You can always go to a family law website for a law firm in your county to find one that is well qualified. You can then check their AVVO rating before you meet with them. Good luck