To increase the number or results on your topic you can use:
Use the asterisk * as a suffix to find all the variations of a word.
The search self-regulat* finds:
self-regulation, self-regulated, self-regulatory, self-regulated, etc.
Use the word OR to search for various synonyms for your topic.
You can combine both the asterisk and OR to increase your results even more.
The search above looks for all the forms of the word math (mathematics, mathematical), as well as algebra and algebraic, and also geometry and geometric.
The EBSCO databases such as ERIC, Education Full Text, and PsycINFO, can be searched in combination to increase your number of results. To do this first open a single database such as ERIC and then click on the "Choose Databases" option at the top of the search page.
Then check the box in front of every database you want to search simultaneously ... and then click on OK.
Alternatively you might try searching larger databases such as Google Scholar or OneSearch.
Warning - though these databases are both huge - they are much harder to focus.