From your description it is understood that you have ED (Erectile Dysfunction) along with a feel of small genital.
ED causes will be checked by physical and lab tests and will be treated, if you reach to a Sexologist.
If Penis is very small (less than 2.5 inch in erect state) penile lengthening surgical procedures may be required for you.
Next Steps
Report for evaluation and therapy before you being sucked into depression . Depression further adversely affects sexual functions.