I would encourage you to try using a 555, you might enjoy the circuit design experience.
I've built very reliable CMOS 555 based boost convertors using I7555C and the BJT NE555.
Requires two external small signal BJT transistors, use one to sense current limit and one to sense output regulation voltage.
My circuit designs will start up at battery voltages as low as 1.75V and deliver 28V and once started will function with battery voltage down to .9V approx with a low threshold N-Chan MOSFET. All together about approx. 14 parts, including 2 small electrolytic caps, 6 resistors, 1 47pf cap, one .1 uf cap, 1 Schottky diode, something between a 10-330 uH inductor.
I use the resulting 28-V power supply to light up a long multiple-string array of 148 or so ultra-efficient white X-Mas LED's on the back porch. In the darker dark of night, viewing up at the 4th floor and with a slowly randomly varying voltage around close to the LED's almost not being lit voltage, the light show is somewhat like a glance at twinkling stars in the heavens above.
The same design works well with NE555 but will not start at voltages <2.7V which can be considered a feature: UVLO protection.
Why use a 555?? Might take a few more components, but it is so common and available and cheap.