Geo Floral Pattern. Digital Skills Needed.

I've recently started hand-drawing patterns that are repeatable. This means you can use your designs in textiles, wrapping paper, wall paper, web backgrounds, etc. I do it the old-school way that involves scissors and tape. I'm sure it's more efficient digitally, but my 4D class at school was a waste and I learned very little as far as Photoshop and Illustrator go. Thus the paper method.

Anyhow, I have this pattern tile that I know will repeat, but I can't figure it out with the few digital skills I do possess. So here it is as a single unit.

Any quick tips as to how I can create a grid of these? I want to see the full pattern repeat, ideally digitally so I can fix any alignment issues (like I'd know how to do that, but one thing at a time). I still want to draw the patterns by hand, because that's what I love, but I want to be able to scan and arrange them using the computer.

Edited to add:

My friend E. is the best ever. She made my pattern repeat digitally and sent it to me last night. Now I just need to convince her to teach me her magic! Also I need access to a larger scanner so I can scan instead of photograph my pattern next time. That will help with the funky shadows and the slightly visible border.