Laptop with low Connectivity

I have an HP Windows 7 laptop that always had fast internet up until 4 months ago. Its been having 2-3, or sometimes 1 bar now. Im trying to use my personal hotspot but thats not even working. My sister has a Windows 7 laptop as well, uses the same internet and still has better internet connectivity than I do. FULL BARS! I know my laptop is capable of having fast speed too, I just don't know how. I think there is a setting or program stopping it from having better connects.How do I fix this?

As downunder said a wifi stick would check if it is your built in adapter, any knocks or blows to it lately?

Also, did you get any 2.4ghz wireless devices lately? Like wireless headphones, keyboards etc? I got caught out by a pair I was reviewing that borked my downloads via wifi but didn't harm the uploads - a bizarre circumstance that took me way too long to diagnose.

Try a Wifi Stick, if it works your build in WiFi is toast.
Assuming you use the latest drivers...