Hi Julien,
seems you are using a STM32F105, but it would make sense to replace it with the more powerful F4, e.g. STM32F405 or STM32F415.
The F1 doesn have a rom based dfu bootloader as the F4, so you indeed need to either use a JTAG/SWD tool or luftboot.
On F4 you can omit the button if you e.g. connect usb vbus to boot0 like on Apogee...
I also noticed that you put a BMP085 on it, latest Aspirin already comes with the MS5611 (which is a better choice nowadays)... so that is probably not needed.
And if you haven't flashed a valid application to it so far, it should go into bootloader mode at startup anyway (if flashing of luftboot was sucessful), and you should see some leds blinking ("knight rider" mode on LisaM, but you have slightly different asignments if I saw that correctly).
Cheers, Felix