It depends on whether you're talking micropenis or just an inch or two smaller than average (which can seem small if you're only used to even slightly above average).
For me girth is more important than length. I'm quite small inside and it doesn't take much to hit my cervix which is uncomfortable. Smaller cocks are also much easier to give blowjobs to!
My DH's, ahem, appendage could probably be best described as short but fat, which suits me perfectly. Best angles for penetration are my legs over his shoulders, me on top 'grinding' or doggy with me on the bed with my shoulders down and my arse up and him standing. It also helps if the guy has his weight under control, as small dick + big gut is not a successful combination and exacerbates the issue.
TMI alert: ironically some of our less successful couplings have been when I've been so turned on I'm too wet for good friction (because the simple fact is it's easier for him to slip out) but luckily his oral skills are second to none so we do other things, or sometimes I'll have a quick wipe to mop up the 'excess' and we'll try again.
I'll be absolutely honest, he is at the lower limit of what I'd find physically satisfying, any smaller or thinner and I think I'd struggle, so I do have sympathy for those who are genuinely tiny (or who are with someone who is) but so much of sex is mental and my DH and I click so well, I'm sure in lots of ways we've had a better sex life than many people who have/are with men with more average-sized or bigger penises. I have the very occasional fantasy about being 'filled' but in reality I'd probably just end up with horrendous cystitis so I never really want to act on it! 
OP, if he is committed to pleasing you and you are compatible in all other ways, try not to overthink or get hung up on his size as you might risk throwing away a great relationship. Only you know if it's a dealbreaker for you, and if any of the suggestions above will work. Good luck.