I know that it would cause dryness, flaking , irration and etc. but would applying alot of retin-a make you even more sensitive to the sun than just applying a thin layer??

I been applying alot more than a pea sized amount of retin-a for a while now.

also is retin-a safe for long term use? long term meaning years

Only use the pea sized amount. Using more can create worst irritation if your skin is sensitive. I think you should be using retin-a at night only. Use a strong sunscreen to protect your skin from the sun.

I was using Retin-a for a year but that is as far as I know. No major side effects for me.

My dermatologist also told me to use a pea-size amount, but it doesn't spread all over my face. How would you explain that?

Yea the pea-size thing is a iffy. I sometimes use alittle more than that since i got hella acne lol. i usually do spot treatment when i use retin-a. be advise though, i recommend that you wear sunscreen spf 30 atleast because your skin is very sensitive to sunlight when you are on retin-a.

which sunscreen do you guys recommend for 30+ spf. I am currently using the olay complete spf 15. I think i should up it to 30spf

i recommend Neutrogena Ultra Sheer Dry-Touch Sunblock, SPF-30. I have very oily skin and this is the only sunscreen that doesnt make feel super oily lol. You might get alittle shine but hey u get protection!.