I’m switching to SubQ

Hello, I’ve talked with my doctor about switching from IM to SubQ as my thigh muscles have been aching so bad lately after doing my injections this way for 1.5 years. They believe I have possible scar tissue in my thighs and maybe I should just take a break from that and switch to SubQ and see how I like it. Well they told me to use 25g 5/8th” needles for injecting and to stick with my belly area 1-2 inches away from the belly button. She got off the phone rather quickly and I didn’t get a chance to ask how exactly I inject, someone told me before on here to pinch the belly fat and inject at an angle. I’m scared to inject into a vein accidentally, should I aspirate the needle to double check? Do I go in at 90 degrees or 45? I see so many different ways people do it. They also told me I can continue doing my 0.3 (6mg) once a week… can I really just do SubQ ONCE a week? I heard it absorbs completely different than IM. If not how could I break up my 0.3ml?

Thanks for any helps. I really appreciate it, I’m so stressed haha.