CRM for a B2B Company

I sell b2b products. I have many lead generating websites that send in leads via email (form submissions). I am looking for a CMS that allows:

• integration with Gsuite/Gmail for contact email history and adding leads to CRM who email directly
• capturing leads from website forms
• marketing emails to subscribers/contacts
• segmentation of subscribers/contacts
• number of marketing contacts around 3000.
• double opt-in (optional)
• multi-branding option

Currently using a combination of Hubspot Starter (2000 contacts @ $100/mo) and MailChimp (1500-2500 contacts @ $47/mon) but want to use one option with a budget of total $50-65/month.