Looks good, but you don't need the housing report, and I would take out the brackets after the photos in the relationship section, so you have (just added a couple of things in blue):
To The Entry Clearance Officer,
Please find enclosed my application and supporting documents for a settlement visa to join my husband in the UK. I would like my visa to start on 01 April 2018, as per the Intended Travel Date on my online application form.
The following documents are included in this package:
Applicant’s Documents:
Receipt for priority processing
Return shipping label
Printed online application
VAF4a Appendix 2
IHS surcharge receipt
Stamped biometrics confirmation sheet
Current US passport
1 Passport photo of myself
Proposed flight itinerary
Sponsor’s documents
Certified copy of husband's passport
Sponsorship letter from my husband
Financial documents
6 months of certified pay slips
6 months of certified bank statements
Sponsor’s employment letter
Accommodation evidence:
Sponsor’s land registry document
Relationship evidence:
Original marriage certificate
2 photos of us together
Original boarding passes from visits
Letters from my husband
Skype and Whatsapp call logs
Please do not hesitate to contact me xxxxx
Yours faithfully,