Hey Joni! After hearing you mention your sister has had hummingbirds across the street from you, and seeing how little these plants are right now, do you have any flowering trees, or other hummingbird plants that are larger and flowering? If she does, and you don't, that might be the reason they're over there, and not in your yard. They'll surely find your feeder sooner or later, but, if you wan't it to be SOONER, you need to take immediate action. Once they have it in their minds that she's the primary food spot and your secondary or tertiary or worse, you won't see many hummers until your plants are much bigger.
It doesn't have to be a million dollars worth of plants, but you need to give them a target in order to lure them away from your sister. It could almost literally be a big red target. Like an old garbage can lid or saucer sled painted bright red with 4 yellow dots on it. Sound familiar? Toss it out in the sun in the middle or your lawn.
If any of the local greenhouses or nurseries have Vermillionaire Cigar Plants, GET SOME! They should be at least 1' tall and full of flowers. Get 4-6 4" pots of them (or as many as you can afford if you want to go all crazy and have hummers by the end of the day).
This is what you're looking for...
Call over to Home Depot 1-815-725-6301 to see if they have any. If not...
Try calling these folks in the morning to see if they have any...
Green Glen Nursery = 1-815-722-3133
Golden Gate Nursery = 1-815-464-6655
Sunshine Garden Center = 1-815-458-6100
You can also ask if they have David Verity Cigar Plants (at the nurseries, HD won't have them), but I find them to be the least drought hardy of these styles of Cigar Plants.
If they don't have either of those, (and do not get cuphea ignea ignea sometimes labeled 'Dynamite', it's a sprawling little ground cover and isn't what you're looking for), get several Black and Blue Salvias. They break like boogers in the wind, but Hummers love them too.
Now get several plants that have lots and lots of bright orange/bright red flowers (they don't have to be hummingbird plants!). It should be something that makes you say "WOW THAT'S A BIG CLUMP OF RED/ORANGE FLOWERS" from across the parking lot as you walk into the nursery. Because that's what you want the hummingbirds to see and then say about the flowers you bring home to your yard. That's the lure you need to get them off of your sister's property and onto yours.
Set them in a sunny spot in your yard where you can see them from your window, and more importantly, where the hummingbirds can see them from your sister's feeder/flowers.
If you have anything to make an elevated platform with (even an upside down garbage can, large empty plant pot or bucket or something similar), set your Cigar Plants on top of it.
Surround it with your bright orange/red "HEY HUMMINGBIRDS!" flowers.
Have a seat inside at an open window (hopefully screened) and make a bunch of chirping kiss noises. Use them to count 1-2-3. Stop. Chirp-kiss-count 1, 1-2. Stop. Repeat or come up with your own pattern if you remember how hummingbirds chirp when flitting about your feeder. Pause for a few minutes and observe your lure for hummingbirds. If no birds are present, chirp-kiss a bit more, pause for a few minutes, repeat as necessary until hummingbirds arrive. Then rest your lips and enjoy the show!
If you want the hummers to come to your back yard, just move the Lure-And-Feed-Flower-Stand (TM 2017 King Cupheaphea) a few feet each day until the stand is in your back yard where you'd like to view the hummingbirds.
Good Luck stealing your sister's, I mean reclaiming your humm, I mean welcoming wee-winged visitors to your yard too!
p.s. For next year, or even now if you have the budget for it, get some Horse-chestnut trees. O'neil Red, and Fort McNair are two popular varieties and are in full bloom right now in my backyard and neighborhood (you'd think I was on the planning commision or something with the number of horse-chestnuts planted throughout the area a few years back) and are the hummingbirds' current 'go-to' plant around these parts.
Have Fun, Be Patient, and Keep Your Eyes Peeled!
The Mighty King Cupheaphea is in Zn 1/2" to the left of your second knuckle from the tip of your thumb on your right palm.