What are my options for inserting a back page into my document?

I'm developing a template for articles and so far I've got the title_page.tex and main_document.tex all sorted out and I'm happy with that.

My problem is I also need to have a back page in the document. I'm finding this quite difficult.

For my title_page, I used the \begin{titlepage} group and then inserted it into the main document with \input{title_page.tex}. I've tried to make a similar .tex file for my back page, utilising the \begin{titlepage} environment.

I want my back page to go after my bibliography. When I insert this, the pagenumbering (I'm using lastpage package) messes up. Is there any way I can seemlessly bolt on a final page to my tex document?

[EDIT]

Thank you for the comments. I have stopped using the titlepage environment. To solve the issue with the page numbering, I just put:

 \addtocounter{page}{-1}

on the back page file. I think that's all I wanted.

Thank you